Rotary thermodynamic apparatus and method

ABSTRACT

Rotary thermodynamic compression and refrigeration apparatus and methods in which the mechanical impedance and/or thermodynamic impedance of the system are controlled in order to obtain stable operation. By controlling these impedances, the overall pressure drop of the fluid flow in the system is made to increase with increasing fluid flow rate, thus ensuring stable operation.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 78,552, filedOct. 6, 1970, now abandoned, which is a continuation-in-part ofapplication Ser. No. 864,112, filed Oct. 6, 1969, now U.S. Pat. No.3,808,828, which is a continuation-in-part of application Ser. No.608,323, filed on Jan. 10, 1967, now U.S. Pat. No. 3,470,704, issuedOct. 7, 1969.

A theoretically higher efficient but impractical refrigerator device hasbeen proposed in U.S. Pat. No. 2,393,338 to J. R. Roebuck, and "A NovelForm of Refrigerator" 16 Journal of Applied Physics 285-295, May, 1945by J. R. Roebuck. The basic form of the device proposed by Roebuch isshown in FIG. 1 of the drawings. The tube 11, which is supported inbearings 10, is rotated at a very high speed about central axis 1 in thedirection indicated by the arrow 12 by means of a drive motor (notshown).

Compressed air is introduced into tube 11 at its inlet 13. It travelsthrough section 2, parallel to the axis, through section 4 towards theaxis, through section 5 parallel to the axis, and exits at outlet 14. Asthe gas moves radially outward it is subjected to centrifugalcompressive forces. While moving in the section 3, the gas is compressedand heated by the centrifugal force created by the rotation of the tube11. At least part of the heat of compression is removed from the gas insection 3 by heat exchange means (not shown) such as water flowing incooling coils.

While moving in section 4, the gas expands, due to the reduction of thedistance of the gas from the axis 1 and the concomitant reduction of thecentrifugal force acting on the remaining mass of gas between it and theaxis, and the gas becomes substantially cooler due to its expansion. Thecooled gas then flows out of the outlet opening 14 for use inrefrigeration.

The system described above is one form of a "rotary inertialthermodynamic system", as the latter expression is used herein. In sucha system is performed a "rotary inertial thermodynamic method", as thatexpression is used herein. Other, greatly improved forms of such asystem and method are disclosed in my U.S. Pat. No. 3,470,704, issuedOct. 7, 1969, and my co-pending U.S. patent application Ser. No.864,112, filed Oct. 6, 1969, now U.S. Pat. No. 3,808,828. Thedisclosures of that patent and application hereby are incorporated inthis patent application by reference.

It is an object of the present invention to provide a rotary inertialthermodynamic system and method in which the fluid flow is stable. It isanother object of the present invention to provide such a system whichis relatively compact, lightweight, uncomplicated and inexpensive, andwhich is capable of operating under a wide variety of conditions and ina wide variety of environments.

In accordance with the present invention, the foregoing objects are metby the provision of rotary inertial thermodynamic apparatus and methodsin which the flow is stabilized by controlling the impedances to fluidflow in the system so that the overall pressure drop of the fluid flowin the system is made to increase with an increasing fluid flow rate.

The foregoing and other objects and advantages will be set forth in orapparent from the following description and drawings.

In the drawings are included several graphs. It should be understoodthat the graphs illustrate the relationships between the variablesqualitatively, and not quantitatively. In the drawings:

FIG. 1 is a schematic drawing of a prior art device;

FIGS. 2 and 3 are graphs used in explaining some of the principles ofthe present invention;

FIGS. 4 and 5 each show separate embodiments of the invention;

FIGS. 6 through 9 are graphs illustrating certain operational featuresof the invention;

FIG. 10 shows, schematically, another embodiment of the invention;

FIG. 11 is a graph illustrating operational principles of the embodimentshown in FIG. 10;

FIG. 12 is a schematic perspective view of a preferred form of thedevice shown in FIG. 10;

FIG. 13 is a cross-sectional view of the device shown in FIG. 12;

FIG. 14 is a schematic drawing of another embodiment of the presentinvention;

FIG. 15 and 16 are graphs illustrating the operation of the device shownin FIG. 14;

FIG. 17 is a schematic drawing of another embodiment of the invention;

FIG. 18 through 21 are graphs depicting the operation of variousembodiments of the invention;

FIGS. 22, 23 and 24 each show a further embodiment of the invention;

FIG. 25 is a graph depicting the operation of the device shown in FIG.24;

FIG. 26 is a schematic drawing of another embodiment of the invention;

FIG. 27 is a graph depicting the operation of the device shown in FIG.26;

FIGS. 28 through 36 each show a separate embodiment of the invention;

FIGS. 37 through 40 show various impedance control devices for theinvention;

FIGS. 41 through 52 and 54 each show another embodiment of theinvention;

FIGS. 53 and 55 are graphs illustrating operational features of thedevices shown in FIGS. 52 and 54, respectively;

FIGS. 56 through 58 show another embodiment of the invention;

FIGS. 59 through 64 each show another embodiment of the invention;

FIGS. 65 and 66 shown another embodiment;

FIGS. 67 and 68 show another embodiment;

FIG. 69 is an elevation, partly schematic view of another embodiment ofthe invention;

FIG. 70 is a cross-sectional view taken along line 70--70 of FIG. 69;

FIG. 71 is a cross-sectional view taken along line 71--71 of FIG. 69;

FIG. 72 is a cross-sectional view taken along line 72--72 of FIG. 69;

FIGS. 73 and 74 each show another embodiment of the invention; and

FIG. 75 is a schematic drawing illustrating certain operational featuresof the invention.

General Principals of the Invention

It will aid in the understanding of this invention to divide thepressure drop in the fluid, as it flows through the rotating conduit ofa rotary inertial thermodynamic system, into a "thermodynamic" componentand "mechanical" component.

The "mechanical" pressure drop is caused by friction between the fluidand the walls of the conduit it flows in. The mechanical pressure dropincreases with F, the fluid flow rate in the system. FIG. 2 shows acurve ΔP_(M) which describes the typical variation of mechanicalpressure drop with flow rate in the device of FIG. 1.

The mechanical pressure drop can be thought of as the pressure drop dueto the "mechanical impedance" to flow through the system.

The second component of total pressure drop is the "thermodynamicpressure drop", ΔP_(T). This component of the total pressure drop isthat caused by thermodynamic conditions of the flow. One example of sucha pressure drop is that caused by the difference in the temperatures ofthe gas in the tube sections 3 and 4 in the device shown in FIG. 1. Thegas in section 4 is cooler and, therefore, denser than the gas insection 3. Therefore, the back pressure created by centrifugal action onthe gas in section 4 is greater than the forward pressure (i.e.,pressure tending to encourage flow in the direction indicated by thearrows in FIG. 1) created by the same centrifugal action on the gas insection 3, with the result that there is a net pressure drop due to thistemperature difference. Other examples of thermodynamic pressure dropswill be given below.

In FIG. 2, curve ΔP_(T) describes the typical variation of theabove-described type of thermodynamic pressure drop with F, flow rate,for the device of FIG. 1. It can be seen that ΔP_(T) decreases withincreasing flow rate, and the curve ΔP_(T) thus has a negative slope.The reason for this is that as the flow rate increases, the amount ofheat removed from the gas flowing in tube section 3 decreases due to thefact that there is a decreasing amount of time for the heat exchangemeans to extract heat from each portion of gas passing through it. Thus,the temperature difference between the gas in sections 3 and 4 decreasesand the thermodynamic pressure drop decreases.

The thermodynamic pressure drop can be thought of as the pressure dropcaused by the "thermodynamic impedance" to fluid flow through thesystem.

In order to calculate the mechanical and thermodynamic impedances of thesystem, an operating point such as point 21 in FIG. 2 is selected. Thentangents 22 and 23 to the curves are drawn. For small fluctuations offlow rate or pressure drop near the operating point 21, thethermodynamic flow impedance is proportional to the slope of line 22,and the mechanical impedance is proportional to the slope of line 23.

In accordance with one basic principle of the present invention, it hasbeen found that stability of the overall rotary inertial thermodynamicsystem can be maintained if the total mechanical and thermodynamicimpedance of the system is positive (for small fluctuations about anoperating point); that is, if the total pressure drop in the systemincreases with increasing flow rate. This relationship is illustrated inFIG. 3. Curve 24 represents a typical system with a total impedancecharacteristic which is positive; i.e. the pressure drop across thesystem increases with increasing flow. Curve 25 represents a systemhaving a total pressure drop which is independent of flow rate. Curve 26represents a system having a total pressure drop which decreases withincreasing flow. For a given flow rate, e.g., the rate at line 27, thefollowing conditions exist.

MECHANICAL IMPEDANCE CONTROL

The system represented by curve 24 can operate stably. Any disturbancewhich tends to increase the flow gives rise to an increasing pressuredrop through the system, which tends to reduce the flow. However, asystem of the type described by curve 25 is not stable. A smallpurturbation of its operation, which would tend to increase the flow,does not give rise to a corresponding increase in pressure drop torestore the system to its initial condition. All decreasing curves, ofwhich 26 is representative, describe systems whose operation isunstable, i.e. any purturbation of the system which tends to increasethe flow gives rise to a reduced pressure drop which, in turn, allowsthe flow to increase further. There is no restorative mechanism topreserve the operation of the system at a stable level of flow.

There are several ways in which the operation of a rotary inertialthermodynamic system can be stabilized in accordance with theabove-stated principles. One of these is to increase the mechanicalimpedance to flow, so that there is a composite impedance which has arising characteristic at the operating point, 27. Another alternative,and one which can be more desirable from the standpoint of efficiencyand flexibility of operation, is to reduce the thermodynamic impedanceand its associated characteristic time lag for the exchange of heat sothat, again, the system has a composite impedance displaying a risingcharacteristic curve, but achieves this condition without sacrifice offlow capability or mechanical efficiency.

FIG. 4 illustrates two different mechanisms by means of which stabilityof the system illustrated in FIG. 1 can be assured. Both use theprinciple of increasing the relative mechanical impedance so that itdominates the thermodynamic impedance, thus assuring a positive totalimpedance.

The first way in which a high mechanical impedance might be obtained isby using a stationary positive displacement pump 28 as the gascompressor. Such a pump is, for example, a reciprocating piston pump, asliding vane pump, or any other pump offering high impedance to the flowof gas to the system from the pump. Cold air from the rotary portion ofthe system flows through refrigeration apparatus (not shown) includingheat exchange means using the cold gas for cooling. Appropriate rotaryseals are used to provide a gastight coupling between the rotary andstationary portions of the system. Relatively dense gases, such as"Freon 12" can be used to reduce the required rotational speed of thedevice. The very high impedance of the pump provides the positiveimpedance which stabilizes the system. It should be pointed out thatthis means of stabilization is not the preferred means, as will be morefully explained below.

Another stabilizing means shown in FIG. 4 is the use of a heat exchanger29 of a form which restricts the gas flow in conduit 11 and thus adds aconsiderable amount of mechanical impedance to the system, and,therefore, reduces the thermodynamic impedance relative to themechanical impedance, and gives a positive total impedancecharacteristic to the system. For example, the heat exchanger 29 can bea porous, thermally conductive plug such as a sintered metal plug; orone with a multiplicity of fine conduits. Metal bodies with many tinyconduits can be formed by use of the technology utilized in theproduction of grids for vacuum tubes by extrusion of a composite bodyand subsequent etching of material from this body to leave finepassages. Other exchanger structures include very finely-formed finstructures produced by extrusion, hobbing, or any of a wide variety ofother techniques well known in the art of constructing heat exchangedevices, and in the art of constructing mechanical damping devices toprovide impedance to the flow of a gas. Of course, the device 29 shouldfunction well as a heat exchanger in order to efficiently remove theheat of compression from the gas in section 3 of the tube 11.

A useful modification of the latter embodiment also is shown in FIG. 4.In this modification, one or more additional conduit sections 33 isconnected in parallel with the first such section. The sectionspreferably are added in opposed pairs in order to maintain rotationalbalance of the rotary portion of the system. A porous plug 29 or similarrestrictor is located in the outwardly-extending section of each suchparallel section. Thus, each separate section contains its ownstabilizing means. This has the advantage of preventing unequal sharingof the fluid flow or even reversal of flow in some sections, which wellmight occur if the only stabilizing means were a single high-impedanceexternal pump 28. Additional plugs 30 can be inserted in theinwardly-extending portions of the conduits to add furtherstabilization.

SINGLE-STATE IMPEDANCE-CONTROLLED THERMODYNAMIC COMPRESSOR

FIG. 5 illustrates the basic features of a compressor constructed inaccordance with the present invention. Thermodynamic compressors of thistype are described in my U.S. Pat. No. 3,470,704 and in my copendingapplication Ser. No. 864,112, now U.S. Pat. No. 3,808,828, as utilizedin a sealed, closed-circuit rotating thermodynamic system to provide theactuating pressure to operate refrigeration apparatus.

FIG. 6 is a graph showing the qualitative relationships between thepressure P and temperature T of the gas in the compressor of FIG. 5.Referring to both FIGS. 5 and 6, a tube 52 like the tube 11 in FIG. 1 isprovided, and is rotated as is the FIG. 1 device. Gas enters tube 52 atan inlet 53 at a pressure P₁₇ and a temperature T₁₇. During the motionof this gas radially outwardly through tube section 50, the pressure andtemperature increase essentially adiabatically to a new pressure andtemperature, P₁₈, T₁₈, corresponding to the pressure and temperature atlocation 48 in FIG. 5. Then, the working fluid returns towards the axisthrough tube section 51. In tube section 51 is located heat exchangemeans 46, such as a porous plug, which is provided to conduct heat froma source (not shown) in the direction of arrow 61 into the working fluidto maintain the working fluid at the temperature which it had reachedduring the adiabatic compression and which it possessed at location 48.Due to the heat exchanger 46, the expansion of the working fluid in partof tube section 51 is essentially isothermal and is represented by theisothermal decrease in pressure to P₂₀, T₁₈, shown in FIG. 6. In theremainder of section 51, the pressure and temperature drop to P₁₉, T₁₉.At each radial distance from the axis of rotation 1 in FIG. 5, a volumeelement in tube section 51 is at a higher temperature than acorresponding volume element at a corresponding radial distance fromaxis 1 in tube section 50. Therefore, the density in such a volumeelement in tube 51 is lower than that of its corresponding element intube 50. Centrifugal forces acting upon the column of gas extendingradially in tube section 51 exert a smaller total backward pressure thanthe forward pressure exerted by centrifugal forces acting on the densercolumn of gas in tube section 50. This gives rise to a net forwarddriving pressure which drives gas through the system in the directionindicated by arrow 54, i.e. P₁₉ is greater than P₁₇. Also, T₁₈ isgreater than T₁₇. Thus, this device acts as a thermodynamic compressorwhich can be expected to have high thermodynamic efficiency.

The same physical effects that give rise to a relationship betweenthermodynamic pressure drop and flow rate for working fluid in arefrigeration system of the type shown in FIG. 1, also give rise to apressure and flow relationship in the case of a compressor of the typeshown in FIG. 5. The compression arises from a difference in temperaturebetween gases in tube section 51 and tube section 50 in FIG. 5. Thistemperature difference is maintained by a flow of heat into the workingfluid as indicated at 61. This flow of heat is not instantaneous, thatis, there is a characteristic time lag associated with the process ofheating the fluid. The faster the flow of working fluid through thesystem, the less exposure time the working fluid through the system, theless exposure time the working fluid has in heat exchange means 46. Thisresults in less effective heat exchange and a smaller temperaturedifference between the working fluid in tube section 51 and that in tubesection 50. Because of this, the thermodynamic pumping action of thispump decreases with increasing flow rate. FIG. 7 shows the relationshipbetween the flow rate F and the pumping pressure ΔP_(T) produced by thecompressor shown in FIG. 5. The above-described behavior is indicatedgenerally in FIG. 7 by curve portion 101, which represents a decrease inthermodynamic pumping pressure with increase in flow.

For the purpose of explanation, suppose that we were to force workingfluid backwards through this pump against the pressure gradiantmaintained by the thermodynamic pumping action. In that case, theworking fluid would be flowing in the direction opposite to thatindicated by arrow 54 in FIG. 5. The first consequence of this reversalin direction of flow is that the portion of tube section 51 which islocated between heat exchanger 46 and the axis 1 no longer containsheated working fluid. The working fluid heated by heat exchanger 46 iscarried radially outwardly and returns towards the axis 1 in tubesection 50. Tube section 50 thus contains heated working fluid. Theregion 48 of the tube 52, which is located further from the axis 1 thanthe radius 63 of the radially outermost point of heat exchanger 46, canbe regarded as an adiabatic region containing heated working fluid whosetemperature and pressure depend only upon the radial distance of thepoint at which temperature and pressure are measured from the axis ofrotation 1. The working fluid returns to axis 1 in tube section 50, andits expansion therein can be regarded as essentially adiabatic. In thetube section 65, between radial distace 63 and the axis 1, thetemperature of the working fluid in tube section 50 is greater than thetemperature of the working fluid in tube section 51 at correspondingradial location. For this reason, the working fluid in tube section 65,when acted upon by centrifugal forces, exerts a smaller pressure in thedirection indicated by arrow 54 than does the corresponding body ofworking fluid in tube section 51, in the direction opposite to the arrow54. For this reason, there is a net pumping action in the reversedirection. This is depicted graphically in FIG. 7 by curve segment 102.As the flow rate in the reverse direction is increased, the workingfluid passing through heat exchanger 46 interacts less efficiently withit. One consequence of this is that the working fluid reaches itsmaximum temperature just at the point where it leaves the heatexchanger. For this reason, the working fluid in tube section 65, atthose radii corresponding to locations within tube section 51 occupiedby heat exchanger 46, has a higher temperature than does the workingfluid within the heat exchanger itself. For this reason, it is possiblefor the pumping action to increase for working fluid flowing morequickly in the reverse direction. If the flow of the working fluidbackwards is made very great, the effect of heat exchanger 46, inchanging the temperature of the working fluid passing through thesystem, becomes essentially negligible. In that case, there is nophysical effect of temperature difference, and the thermodynamic pumpingpressure differential goes asymptotically to zero for large flows.

The most pronounced feature illustrated by FIG. 7 is that thethermodynamic pumping mechanism can work to pump working fluid in eitherthe positive flow direction or the negative flow direction. There is anarrow region within which the pressure of the thermodynamic pumpingaction in the two different directions is joined, here designated bydashed curve segment 103. The details of the form of curve segment 103depend upon the details of heat exchange and convection and areprofoundly affected by the geometry of the device. However, essentiallynone of the possible variations of the geometry can stabilize the systemat the zero flow point. Note that the pumping effect is an increase inpressure at the output compared to the pressure at the intake for thepumping system. For this reason, it has a negative sign, compared topg,17 a mechanical resistance to flow, and is designated in FIG. 7 by -ΔP_(T).

FIG. 8 illustrates the relationship between the flow rate F and themechanical pressure drop ΔP_(M) in the device of FIG. 5. Mechanicalresistance to flow always opposes the flow, i.e. for a positive flowthere is a positive drop in pressure, taking the inlet pressure minusthe outlet pressure. Using that convention, for a positive flow there isa positive ΔP_(M), and for a negative flow a negative ΔP_(M). This isindicated schematically by curve 104 in FIG. 8. Note that in the regionnear zero flow rate where there is the greatest problem in stabilizingthe thermodynamic compression mechanism, the effect of the mechanicalimpedance to flow is the least.

The overall performance of a single pumping loop of the type illustratedin FIG. 5 is represented graphically in FIG. 9. ΔP in FIG. 9 is thetotal pressure difference, defined as pressure at inlet 53 minuspressure at outlet 49, for compressor 52 in FIG. 5. ΔP is defined as thealgebraic sum of the mechanical pressure and the thermodynamic pressuredifferences, observing the sign convention defined above. Curve portion105 in FIG. 9 represents flow in the forward direction, and portion 106represents flow in the reverse direction. The curve portion in thefourth quadrant represents operation of the system as a compressor,driving its own flow in the forward direction. The region in the secondquadrant represents the compressor driving its own flow in the reversedirection. ΔP, for small reverse flow, is represented very approximatelyby dashed curve portion 108. The intersection of a line 107 and line 105is a selected operating point Q, with flow F_(Q) and compression C_(Q).The following equation expresses the relationship between C and F: C = -ΔP(F), when ΔP(F) is a function of the flow F. Line 109 is tangent tocurve 105 at the operating point Q, and the slope of line 109, for smallfluctuations of flow near point Q, gives a measure of the rate of changeof ΔP with F. It can be seen that the tangent line 109 is positive.Thus, the compression C which serves to drive the flow F in the forwarddirection decreases with increasing flow. For this reason, operation ofthe system at the selected operating point Q, is stable with respect tosmall fluctuations in flow. A fluctuation tending to increase the flowdecreases the driving compression available to continue the flow. Thisallows the flow to return to its original value. Similarly, afluctuation which tends to decrease the flow increases the amount ofcompression available to drive the flow, which in turn restores the flowto its original value. It is important to select the operating point Qfar enough from the zero flow point so that fluctuations in thetemperatures and pressures of operation of the system will not producean excursion in the flow rate sufficient to take the flow from itsselected operating point through the zero value and force the systeminto operation in a reverse flow mode.

One of the most important single aspects of the operation of a rotaryinertial thermodynamic compressor of the kind shown in FIG. 5 is thatstable operation requires that the forward flow be substantiallydifferent from zero. Thus, stable operation of the compressor requiresthat the external impedance not be so large in relation to the internalimpedances of the compressor as to reduce the flow to such a small levelthat the fluctuations in the pressure generated by the compressor or inthe pressure reflected by the external load would force the flow ofworking fluid to reverse, even briefly.

CASCADED IMPEDANCE-CONTROLLED THERMODYNAMIC COMPRESSOR

FIG. 10 shows, schematically, a compressor 199 in which severalsingle-loop compressors of the type shown in FIG. 5 are connectedtogether in series ("cascaded") in order to provide an increase incompression over that available from a single loop. Such a cascadedcompressor is particularly desirable in uses in which it is notpossible, because of limitations on input and output temperature,rotational speed, size of the device, or because of the nature of theworking fluid, to achieve the desired compression with stable operationin a single loop. The compressor 199 includes a conduit 200 which hasthree U shaped loops. At appropriate places within the conduit 200 arelocated heat exchangers, e.g., porous plugs, 133, 135, 137, 139, and141. Working fluid (gas) enters the system at inlet 131 and travelsradially outward through conduit section 132, experiencing essentiallyadiabatic compression. It returns towards axis 1 in conduit section 134,passing first through heat exchanger 133 within which it experiencesexpansion, which can be regarded as essentially isothermal. The workingfluid then continues towards axis 1 through region 144 of conduitsection 134, within which its continued expansion as it approaches axis1 is essentially adiabatic. In moving from inlet 131 to station 201,located on the rotational axis 1, the working fluid has passed through arotary thermodynamic compressor stage essentially like that described inFIG. 5. In FIG. 10 this first stage of compression is given referencenumeral 202. Second and third stages 203 and 204 follow stage 202.

The second stage 203 includes conduit sections 136 and 138, and heatexchange means 135 and 137. Working fluid continues from station 201through heat exchange means 135, moving radially outwardly. Within heatexchange means 135 the compression of the working fluid can be regardedas essentially isothermal, i.e. the heat exchanger 135 allows heat tocompression to leave the working fluid during compression. After passingthrough heat exchange means 135, the working fluid continues through theregion 145 beyond heat exchanger 135, within which its compression, asit moves radially outward, is essentially adiabatic. The working fluidthen returns to axis 1 through heat exchanger 137, within which itsexpansion on returning towards the axis is essentially isothermal, andthen through conduit region 146, within which its further expansion isessentially adiabatic.

The working fluid next flows through the third stage 204, in which it isacted upon in substantially the same manner as in the second stage 203.The compressed gas emerges from an outlet opening 143.

It should be understood that heat is added to the working fluid from oneor more heat sources through each of the heat exchangers 133, 137 and141 so as to maintain the flow through those exchangers essentiallyisothermal.

Fig. 11 shows the relationships which are believed to exist between thepressure and temperature of the working fluid as it passes throughcompressor 199 shown in FIG. 10. Point 149 represents the pressure andtemperature of the working fluid at the inlet 131. Line segment 150describes the adiabatic compression of the working fluid in conduitsection 132. Line segment 152 describes the isothermal expansion ofworking fluid returning towards axis 1 in heat exchanger 133. Linesegment 154 describes the adiabatic expansion of working fluid withinregion 144 of conduit section 134. The point 155 gives the pressure andtemperature of the working fluid at station 201 in FIG. 19. This is itstemperature and pressure after having completed passage through thefirst compressor stage 202. The arrows next to the various portions ofthe curve in FIG. 11 indicate the progress of a volume element ofworking fluid through the compressor 199.

The difference in pressure between points 155 and 149, designated C₁,represents the compression provided by the first stage 202 ofcompression.

In the second stage of compression, line segment 156 designates theisothermal compression of working fluid within heat exchanger 135. Linesegment 157 represents the adiabatic compression or working fluid withinregion 145 of conduit segment 136. Line segment 159 represents theisothermal expansion of working fluid within heat exchange means 137 inconduit segment 138. Line segment 160 represents the essentiallyadiabatic further expansion of working fluid in region 146 of conduitsection 138. Point 170 represents the pressure and temperature atstation 205. This completes the second stage of compression 203, and thecompression provided by this second stage is designated C₂ in FIG. 11.

Compression stage 204 is represented by line segments 171, 172, 173 and174, corresponding respectively to isothermal compression within heatexchange means 139 of conduit segment 140, adiabatic compression withinregion 147 of conduit 140, isothermal expansion within heat exchangemeans 141 of conduit segment 152 and adiabatic expansion in region 148of conduit segment 152. Point 161 in FIG. 11 represents the pressure andtemperature of the working fluid at outlet 143 of the compressor 199.The difference in pressure between point 161 and point 170, designatedC₃ in FIG. 11, is the compression occurring within the third stage 204of the compressor. The total compression provided by the entirecompressor is represented by the difference in pressure between point161 and point 149 (the sum of C₁, C₂ and C₃), and is designated in FIG.11 by C.

The provision of adiabatic compression in the first section 132 of thecompressor 199 is optional. If desired or necessary, a heat exchangerpositioned like heat exchangers 135 and 139 can be used to make thecompression isothermal. Ordinarily, however, the gas entering thecompressor will be cool and isothermal compression in the first stagewill be unnecessary.

Except for the above-described optional feature of the first stage ofthe compressor 199, all of the stages preferably are essentiallyidentical to one another.

There is another, perhaps simpler, way to analyze the behavior of thecascaded compressor 199. The compression produced by a rotarythermodynamic compressor of the form illustrated in FIG. 5, depends uponthe input pressure for the device, assuming that all other operatingparameters are held constant. This approximation applies to the casewhere the flow of working fluid through system is not so great as torender heat exchange within the heat exchange means relativelyineffective. This proportionality between the compression in a singlestage and the input pressure to that stage is a consequence of theproduction of pressure by the action of centrifugal forces on thecolumns of gas within tube sections 65 and 62 in FIG. 5. The totalpressure in the forward direction, as designated by arrow 54, producedby the column of gas in tube section 65 depends upon the centrifugalforce acting upon the mass of gas in that tube section. The reversepressure produced by working fluid in tube section 62, trying to forceworking fluid against the direction indicated by arrow 54, also dependsupon the action of centrifugal forces on the mass of the working fluidpresent within column 62. The difference in density between the workingfluid in the two columns, 65 and 62, is a consequence of a difference intemperature within those two columns. For an ideal gas the ratio of thedensity in one column 65 to the density in the other column 62 dependsupon the ratio of the temperatures. For a fixed relationship intemperatures the absolute difference in density between the workingfluid in the two columns is proportional the absolute density of theworking fluid. This density, in turn, depends upon the overall pressureof the working fluid within the system, and, for relatively small flowrates, is explicity a single-valued function of the pressure at theinlet to the compression stage. Thus, for an ideal gas, the absolutedifference in pressure produced by the operation of a single-stage of arotary thermodynamic compressor is proportional to the pressure at itsinlet. This behavior for a cascaded compressor is illustrated in FIG.11. The pressure difference C₂ produced in the second stage ofcompression, is not as large at the pressure difference C₃ produced inthe third stage. This is because the inlet pressure at the intake to thesecond stage of compression is not as high as the inlet pressure at thethird state. In FIG. 11, operation is assumed to be with a working fluidwhich is an ideal gas, and the pressure increment for each stage ofcompression after the first stage is roughly proportional to the inletpressure for that stage. One consequence of this physical effect is thatoperation of a rotary thermodynamic compressor with many stages can becharacterized as a multiplication of the inlet pressure by a ratio,which, for flows not so large as to render the operation of the heatexchange means within the system relatively ineffective, nor so large asto cause appreciable friction, is independent of both inlet pressure andflow. This leads to an exponential dependence of the form shown in thefollowing equation:

    P.sub.out ≃P.sub.in R.sub.p.sup.N

in which P_(out) is the outlet pressure, P_(in) is the inlet pressure,R_(p) is the compression ratio for each stage and N is the number ofstages in cascade.

Cascading rotary thermodynamic compressors of this form is a way toachieve capability of delivering working fluid at a higher pressure thanwould otherwise be possible. This increases the resistance to reverseflow through the compressor, and thus increases the impedance of a loadto which such a compressor system can stably deliver working fluid.Moreover, because the output pressure increases exponentially with thenumber of cascaded stages, cascading the stages results in a greatertotal impedance than the sum of the individual impedances of each stageoperating along, and thus stabilizes the compressor substantially moreeffectively than might be considered to be possible.

One modification of the compressor 199 can be formed by using severalparallel branches, each of which contains several stages in cascade, inorder to deliver a larger volume of working fluid, and in order toprovide flexibility in the geometric arrangement of the various pumpingstages within the device. For instance, such parallel branches can beused to provide for dynamic balance of the system when it is workinginto various gas pressure loads.

HELICAL-TOROIDAL THERMODYNAMIC COMPRESSOR

FIGS. 12 and 13 show a cascaded multi-stage thermodynamic compressor 500with stages like those shown in FIG. 10, but arranged in a particularlyadvantageous formation.

As is shown schematically in FIG. 12, the compressor 500 includes twogroups of loops 510 and 512 of tubing. Each group of loops is formed bywinding a single length of tubing in a pattern tending to form a toroid.Each loop 510 is opposite to a loop 512 in the opposite group, and theloops are arranged symmetrically with respect to the central axis 517 ofthe toroid.

The starting end of the upper group of loops 510 is connected to thestarting end of the opposite group 512. This connection is indicated byreference numeral 516. Similarly, the trailing ends of the groups areconnected together as indicated at 518. Thus, the two groups areconnected together in parallel. A refrigeration unit or other load 519is connected to the conduits 516 and 518. The refrigeration unit 519contains, for example, means of the type described above forcentrifugally compressing, expanding and returning a working fluid tothe compressor 500 through the conduit 516. The compressor 500 and therefrigeration unit 519 are connected together to be rotated as a rotaryheat pump unit by a motor 504.

As is shown in FIG. 13, the loops 510 and 512 are secured between a pairof heat-conducting metal plates 506 and 508 by means of welding orsoldering. The plates 506 and 508 are secured to a hollow shaft 502through the center of which pass tubes 516 and 518. Insulation 514 fillsthe toroidal hole formed by the loops 510 and 512. The plates 506 and508 may have suitable heat transfer fins on their outer surfaces.

The various compression stages are arranged so that all of the heatexchangers 135, 139, etc., through which heat is rejected contact theplate 508. Heat is conducted into plate 506 from the working fluid, andis dissipated from plate 508 into the environment. Similarly, heatexchange means 133, 137 and 141, through which heat is absorbed into theworking fluid during expansion, make thermal contact with the plate 506through which heat flows into the working fluid.

The compressor 500 operates as follows: Heat is added to the portions ofthe loops in which the working fluid flows toward the axis 517 byheating the plate 506, and the portions of the loops in which the fluidflows away from the axis 517 are cooled by cooling the plate 508.Rotation of the loops augments the pressure difference between theoutwardly and inwardly flowing fluid columns in each loop in the mannerdiscussed above. Since the loops in each group are connected together inseries, the compression produced by each loop multiplies that producedby the preceeding loops in the group, with the result that relativelyhigh total fluid pressures can be produced with working fluids ofrelatively low density, or with the use of relatively low rotationalspeeds, or with rotary devices having relatively small diameters.Alternatively, rather than using this embodiment of the invention toreduce the foregoing parameters, it can be used simply to produce veryhigh total fluid pressures.

The arrangement of the loops into two parallel-connected groups is madein order to ensure that opposite portions of the rotary structure willhave the same amounts of fluid in them at the same time and therotational balance of the structure will be maintained. Additionalparallel-connected groups can be added as desired.

EXTERNAL IMPEDANCE

All of the rotary thermodynamic devices discussed so far have in commonthe same physical principle of operation. This is true independent ofwhether the system is used for cooling or for compression, whether thesystem has a single branch through which fluid can pass or multiplebranches in parallel, whether the system has a single stage or a seriesof cascaded stages, whether the system is part of a closed rotatingloop, or is open in the sense that working fluid enters and leaves therotating assembly. The principle of operation which all of these deviceshave in common is the interaction within a rotating system of inertialforces which arise within the rotating system and the thermodynamicproperties of a working fluid. These inertial forces are known ascentrifugal forces and coriolis forces. The centrifugal forces are thefamiliar forces which tend to throw material out toward the rim of aspinning chamber. The coriolis forces are those which act upon materialmoving outwardly in a duct to bring it up to speed so that itstangential velocity about the axis matches that of the channel withinwhich it is moving. Similarly, when material is moving from near theperiphery to near the axis, coriolis forces act to slow down thematerial so that when it reaches the axis its tangential velocity hasbeen reduced from that which it had near the periphery. It is theinteraction of these rotary inertial forces with differences in densityof the working fluid, associated with differences in temperature, whichlink thermodynamic work in the form of the flow of heat to thermodynamicwork in the form of flow of a pressurized working fluid within thesesystems. It is this relationship between thermodynamic flows of heat andmechanical flows of working fluid which gives rise to the characteristicdynamic properties discussed above. The dynamic instabilities which havebeen discussed are, therefore, a characteristic property of rotaryinertial thermodynamic devices. These instabilities arise when there isan improper relationship between the thermodynamic impedances andmechanical impedances for the various parts of the thermodynamic deviceand the other parts of the system, of which it is a component. Themechanical impedance to the flow of working fluid within a rotaryinertial thermodynamic device may be regarded as a property of thedevice itself and the external flow impedance to which it is coupled.The thermodynamic impedances presented to working fluid within thesystem include both the thermodynamic impedances for exchange of heatwithin the device itself and also the thermodynamic impedances externalto the flow of the working fluid proper. All of these thermodynamicimpedances should be considered in determining the stability of flow ofworking fluid within the rotary inertial thermodynamic device.

For example, suppose that the cooling device diagrammed in FIG. 4 had intube section 3 a very efficient heat exchange means for allowing heat toflow from the working fluid during its compression into the heatexchange means itself. Suppose, however, that this heat exchange meanswas only relatively ineffectually linked to an external sink to whichthis heat could be dissipated. The ability of the heat exchange means toremove heat from the working fluid during compression would then depend,not only upon the effectiveness with which the heat in the working fluidcould be exchanged with the heat exchange means itself, but also uponthe effectiveness with which this heat exchange means could dissipatethe heat to some other part of the system. This total thermodynamicimpedance is what characterizes the thermodynamic impedance presented tothe working fluid. If this total thermodynamic impedance is very high,even if there is only a relatively small flow, the system will not becapable of dissipating the heat of compression from the working fluidand will have a rapid drop in the back-pressure by which it acts to usethe pressure of the working fluid entering the system to producecooling. If, on the other hand, the total thermodynamic impedance withrespect to the working fluid in tube section 3 is very small, even whenthere is a relatively large flow of working fluid a cooling effect canbe expected.

HEAT SOURCE IMPEDANCES

The characteristic thermodynamic impedance of the heat source is anotherimpedance of the system which should be taken into consideration instabilizing a rotary inertial thermodynamic system. The impedance of aheat source is analogous, in some respects, to the internal impedance ofa source of electrical energy.

In this analogy, heat flow corresponds to electrical current, andtemperature corresponds to voltage. Thus, a high-impedance heat sourceis one in which the heat flow is relatively constant regardless of thetemperature of the medium into which it delivers heat. Conversely, alow-impedance heat source is one in which the temperature is relativelyconstant regardless of the amount of heat flow in to the medium. Hence,a high-impedance heat source is analogous to a constant-currentelectrical source, and a low-impedance heat source is analogous to aconstant-voltage electrical source.

Examples of high-impedance heat source are flames and hot air. Anexample of a low-impedance heat source is a relatively large body of hotwater. Other examples of both types of heat sources will be given below.

As an example of the influence of the impedance of the heat source onthe stability of a rotary inertial thermodynamic device, consider thedevice shown in FIG. 5. The heat exchange means 46 in the tube section62 is coupled to an external source of heat which has, of course, acharacteristic thermodynamic impedance. If the impedance of the heatsource is very high, as the flow rate of working fluid through thecompressor 52 decreases because of an increasing back-pressure againstwhich the system must deliver working fluid, the amount of flow ofworking fluid past heat exchange means 46 available to take heat awayfrom it decreases, and, therefore, the temperature of heat exchangemeans 46 increases. The result of this increase in temperature of heatexchange means 46 is that the density of working fluid in tube section62 decreases, increasing the effective compression available from therotary inertial thermodynamic system. Thus, the use of a heat sourcewith high thermodynamic impedance tends to stabilize the operation ofthe compressor in the presence of large back pressures from externalloads in that the higher compression enables the device to better resistreversal of flow from the load back through the compressor.

IMPEDANCE-STABILIZED CLOSED-LOOP ROTARY INERTIAL HEAT PUMP

The principles discussed in the preceeding section can be utilized toensure the stable operation of a wide variety of rotary inertialthermodynamic systems, including a closed-loop rotary inertialthermodynamic system 300 of the form described in my U.S. Pat. No.3,470,704 and shown schematically in FIG. 14. The device 300 has acompressor section 311, and a cooling section 312. The compressorsection includes conduit sections 301 and 302, heat exchange means 303,and an expansion region 304 within conduit section 302. Compressor 311is a rotary inertial thermodynamic compressor. The cooler section 312includes conduit segments 305 and 308, and heat exchangers 306 and 309.Heat exchangers 306 and 309 extend for a substantially the full lengthsof conduit sections 305 and 308. Cooler 312 is a rotary inertialthermodynamic cooler. Conduit section 310 completes the closed loopconduit.

The operation of rotary inertial thermodynamic compressor 311 ischaracterized by FIG. 15 which is a graph relating the change inpressure in the compressor and the cooler to the rate of flow of workingfluid through the system. Note the sign convention for pressure change,which leads to a representation of P of the compressor being negative,i.e., the drop in pressure of working fluid flowing through it isnegative; the pressure produced is positive.

The properties of the cooler 312 are represented by curve 313 in FIG.15. It can be seen that P for the cooler decreases at first withincreasing flow, as the thermodynamic back-pressure decreases. Atrelatively high flow rates, mechanical impedances dominate and thepressure drop through the system again rises. Note that the rate of dropof curve 313 in FIG. 15, representing the back-pressure generated in thecooler, is a consequence of a loss of heat from the working fluid duringcompression in tube section 305 by means of heat exchange means 306, andthe gaining of heat from the environment during expansion of the workingfluid in tube section 308 by means of heat exchange means 309.

If the thermodynamic coupling of heat exchange means 306 and 309 totheir environments is very poor, then the rate of drop of theback-pressure generated in cooler 312 would be much steeper than thatshown in curve 313. The relationship of back-pressure flow for thiscondition to is represented by dashed curve 315 in FIG. 15.

FIG. 16 shows a curve 317 relating the total pressure drop through boththe compressor 311 and the cooler 312, acting in series, to flow rate F.Stable operation of the system as a closed loop occurs when the totalpressure drop in going aroung the loop is zero, and the slope dP/dF ispositive. Curve 317 passes through zero total pressure drop at anoperating point 316. Flow in the system at point 316 is stable andefficient. Limitations on the flow of the working fluid arise primarilyfrom thermodynamic effects, rather than from mechanical, frictionalconstraints.

Curve 318 in FIG. 16 represents the total pressure drop in compressor311 and cooler 312 in the case in which cooler 312 has only very littlethermodynamic coupling to its environment. That is, curve 318 representstotal pressure drop for the same conditions represented by curve 315 ofFIG. 15. Curve 318 represents the algebraic sum of curves 315 and 314.Curve 318 crosses the zero axis at an operating point 319. This pointrepresents a condition in which the working fluid is circulating veryrapidly through the system and the amount of work done by the workingfluid against the thermodynamic pressure drop within cooler 312 is verysmall. The principal limitations on the flow are caused by friction.

The efficient operation of the rotary inertial thermodynamic device 300as a heat-actuated cooling system requires that the flow of workingfluid within the device be limited principally by thermodynamic effectsrather than by mechanical friction of the working fluid within theconduits and heat exchangers through which is passes. The reason forthis is that the mechanical friction on the working fluid is anirreversible thermodynamic loss. Thus, to achieve stable, efficientoperation of the device 300, it is desirable that the cooler 312,regarded as a total system (including those parts of its environmentwith which it exchanges heat) present a lower thermodynamic impedancethan is presented by the compressor 311, regarded as a total system(including those parts of its environment with which it exchanges heat).If the foregoing constraints on thermodynamic impedance cannot readilybe met, the operation of the system can be stabilized by inclusion,anywhere within the conduit, of a flow restricting means 320 (FIG. 14),for instance a constriction or a porous plug in the conduit. This flowrestrictor can advantageously be combined with one of the various heatexchange means present within the conduit, although it is not necessaryto make such a combination.

IMPEDANCE-STABILIZED OPEN-LOOP ROTARY INERTIAL HEAT PUMP

As a second example, consider the problem of the stability of an "openloop" rotary inertial thermodynamic system; e.g., a system of the typeshown in FIG. 4 in which a stationary source of working fluid is used. Aparallel-branch embodiment 349 of such a system is shown schematicallyin FIG. 17, in which 360 is the inlet, and 361 is the outlet. The devicehas four branches 350, 351, 352 and 353, containing, respectively,compression sections 348, 357, 358 and 359, which contain, respectively,heat exchangers 347, 354, 355 and 356. These heat exchange means arecoupled to an external environment, into which they can reject the heatof compression which they receive from the working fluid as it iscompressed.

FIG. 18 shows a curve 362 relating the frictional (mechanical) pressuredrop of working fluid in passing through one of the branches (which areassumed to be identical) to the flow F of working fluid through thatbranch, and a curve 363 relating the thermodynamic pressure drop to thesame flow. In FIG. 19 the curve 364 relates the total pressure dropwithin each branch to flow. Curve 364 is the algebraic sum of curves 362and 363 in FIG. 18. An operating point 365 is selected at the point oftangency of a tangent line 366 which has a positive slope.

By making the mechanical impedance in each one of the branchessufficiently large, the pressure drop within that branch can bedominated by the mechanical impedance, rather than by the thermodynamicimpedance. In this way, it is possible to select an operating pointwhere the curve 364 has a positive slope, i.e., a small increase in theflow through that branch would be accompanied by an increase in thepressure drop within the branch. This means that the flow through thebranch would decrease. Similarly, any decrease in the flow through thatbranch would lead to a decrease in the pressure drop, thus allowing theflow to increase. Therefore, the flow at the operating point 365 isstable.

The mechanical impedance can be simply the impedance of the heatexchanger in that branch. Separate flow restrictors also can be used.The high mechanical impedance necessary for stability causesirreversible thermodynamic losses. For this reason, although themultiple-branch cooler 349 shown in FIG. 17 might appear attractive, adetailed analysis, including an analysis of possible dynamicinstabilities, shows that its thermodynamic efficiency is not nearly ashigh as in alternative embodiments disclosed herein.

The length and positions of the heat exchangers in the conduits is afactor to be considered in the construction of rotary inertialthermodynamic devices. Consider the case where the rotary inertialthermodynamic device in FIG. 4 is operated as a single-branch compressorof the type in FIG. 5 with heat supplied to heat exchange means 30.Consider first the case where heat exchangers 29 and 30 are relativelyshort, and exchanger 29 is placed near the axis 1, and exchanger 30 isremote from the axis. For this discussion, it is assumed that fluid inthe rest of the system is relatively cool. Assume also that flow isopposite to the arrow 31. This causes region 4 to be filled with coolworking fluid, and region 32 to be filled with the working fluid whichhas been heated by its passage through heat exchanger 30. The result isthat, even for small reverse flows (in a direction opposite to arrow31), the system ceases to operate as a compressor driving working fluidin the forward direction and begins to drive working fluid in thereverse direction.

FIG. 20 is a graph illustrating the operation as a compressor of thedevice shown in FIG. 4 with varying lengths of the heat exchangers 29and 30. Frictional effects are included. Curve 409 represents flow inthe forward direction indicated by arrow 31. Curve 412 representsreverse flow with short heat exchangers positioned as described above.Curve 411 represents conditions identical to those of curve 412, exceptthat the heat exchangers are longer, and curve 410 represents the casein which the exchangers are so long that they substantially fill thetube sections in which they are located.

The change from forward to reverse flow results in a sudden change G₁ orG₂ in the compression available. As the heat exchangers are elongated tofill progressively larger portions of the conduit segments, the effectproduced by changing the temperature of the working fluid in sections 32and 4 becomes smaller. For small flows, it is assumed that the workingfluid within heat exchangers is essentially the temperature of the heatexchanger. Therefore, the change in pressure appearing for small flowsin the reverse direction is reduced by extending the length of theseheat exchangers. Thus, with the longest heat exchangers, the change inpressure appearing upon reversal of flow through the system isessentially zero. However, extending the length of the heat exchangersbeyond the length required to produce the isothermal compression andexpansion required for operation in the Carnot cycle reduces theefficiency of the system. This is because the region 32 for adiabaticcompression and the region 4 for adiabatic expansion become very small.This does not allow adequate compression to occur in section 32 to allowthe working fluid to achieve at station 15 a temperature equal to thatof heat exchanger 30. In the case of reduction of length of adiabaticregion 4, the result is that working fluid leaving the system throughoutlet 34 is at a higher temperature because it has had less adiabaticexpansion to reduce its temperature from that which it possessed uponleaving heat exchanger 30. The result is that the thermodynamicefficiency of the system is decreased at the same time that the gap inpressure upon small reversal of flow of working fluid through the systemis decreased.

Dashed curve 417 in FIG. 20 represents pressure variations with smallflows in the forward direction in a device as shown in FIG. 4 used as acompressor in which the heat exchange means has a relatively highthermodynamic impedance to the flow of heat from the external heatsource into the working fluid. This high thermodynamic impedance can becaused either by the high internal impedance of the source itself, or ahigh thermodynamic impedance to the flow of heat into the working fluid,or by both. The result of this high impedance is that, for small flowsof working fluid forward through the compressing system, the temperatureof heat exchanger 30 increases so that the amount of compressionavailable, due to the difference in density of the fluid in theoutwardly and inwardly directed segments of the conduit 11, increases.

Systems represented by the graph 409 in FIG. 20 can be said to beconditionally stable, i.e., if they are operated at an operating point420 for which the flow in the forward direction is sufficientlydifferent from zero so that fluctuations in flow are very unlikely todrive the flow into the reverse mode, then the system will operateproperly as a compressor, driving working fluid in the forwarddirection. Such compression systems can be made unconditionally stable,i.e., stable independent of whether they are forced in a reverse mode ornot, by coupling them with mechanical impedance means (e.g., fluid trapsdisclosed in my above-identified pending patent application and hereinbelow) providing a relationship between flow and pressure as indicatedgraphically in FIG. 21. In FIG. 21, curve 415 represents flow in theforward direction through this impedance, curve 416 represents flow inthe reverse direction through the impedance, and the gap G₃ in thepressure in the region of zero flow represents the change in pressurerequired to force this impedance into the reverse flow mode. As long asgap G₃ is larger than the gap, G₁ or G₂ (FIG. 20), appearing when thecompressor is forced into reverse flow at small flow levels, the systemwill be unconditionally stable in the vicinity of zero flow. Operationin this mode is illustrated graphically in FIG. 21 by curve 413 (forwardmode) and curve 414 (reverse mode). Gap G₄ represents Gap G₃algebraically summed with gap G₂, and is the amount of pressurerequired, beyond the back-pressure at which the compressor has zeroflow, to force flow backwards through the compressor. Note that at nopoint does curve 414 enter the second quadrant of the graph, which wouldrepresent pumping of working fluid in the reverse direction.

Also, there is a gap G₅ between the greatest forward compression and theleast reverse flow pressure. This ensures that a set of parallelbranches of a compressor can operate together without some branchesforcing working fluid back through others.

PARALLEL-BRANCH INSTABILITIES AND STABILIZATION

Although the basic physical nature is the same, there is a usefuldifference between the form of instability which occurs in a gaseousrotary inertial thermodynamic cooler containing a set of branchesconnected in parallel and that which can occur in a rotary inertialthermodynamic compressor containing a set of parallel branches. In thecase of the cooler, the instability is believed to consist of anexcessively rapid flow of working fluid through one of the branches ofthe system. In this type of instability, working fluid flows through thebranch in the desired direction. In the case of the compressor, the formof the instability is believed to be that the flow through one branch ofthe compressor is reversed. Therefore, there are a number of techniqueswhich can be used in the compressor to avoid this reversal of flow andthereby make the system unconditionally stable which are not availablefor use in stabilizing the cooler. This is made especially clear by FIG.21.

One of the simplest devices which will produce the assymmetric behaviorwith respect to flow, represented by FIG. 21, is a check valve. Forexample, this could be a flap valve or ball valve which opens to allowflow in the forward direction and closes to prevent flow in the reversedirection. Alternatively, it could be a liquid trap as disclosed and asis shown in FIG. 22 of the drawings herein.

FIG. 22 shows an impedance control means 420 with an outwardly-extendingconduit section 421, an inwardly-extending section 424, and a broadchamber 422 between sections 421 and 424. The chamber 422 has an inletport 427. The liquid 423 is held against the outer wall 425 of thechamber 422 by centrifugal force caused by rotation of the device aboutthe axis 1. For a gaseous working fluid to flow in the directionindicated by arrow 428, it need have only enough pressure to bubble upthrough the shallow liquid 423 in chamber 422 and then out through exitconduit section 424. For the gas to pass through the trap in theopposite (reverse) direction, the gas must push liquid 423 back up intoconduit section 421 a substantially greater radial distance than it mustpush the liquid in order to flow in the forward direction. Thisintroduces a pressure gap corresponding to G₃ in FIG. 21, and, ineffect, forms a type of check valve. Branches identical to the one shownin FIG. 22 can be connected in parallel if desired.

FIG. 23 shows a compressor 430 like that shown in FIG. 5, except that ithas plural parallel branches instead of one, a plenum 431, and a flapvalve 432 near the outlet of each branch. This compression system isunconditionally stable against excessive back-pressure at outlet 49.Additional branches, each with its own check valve 432, can be added asdesired.

It is possible to use several forms of stabilization simultaneously inthe same device. For instance, the heat exchangers might be coupled tohigh-impedance heat sources so as to enhance the protection againstreversal of flow. Examples of high-impedance heat sources which might beutilized in this way are, in addition to a flame burning a fixed amountof fuel per unit time, the decay of a radioistope heat. source, radiantheating, electromagnetic inductive heating, etc. In another embodiment,the same electromagnetic induction field which transfers thermal energyto the heat exchangers might also provide a rotating electromagneticfield which, by its electromagnetic drag on the rotating system, rotatesthe device about the axis 1. For practical reasons, generally it ispreferable that this high impedance be achieved by having a highthermodynamic impedance between the environment and the heat exchangemeans, rather than by a high impedance between the heat exchange meansand the working fluid itself. This insures that the heat exchange meanswithin the compressor will not have a temperature very much higher thanthat of the working fluid and tends to protect the working fluid fromthermal degradation.

Use of an unconditionally stabilized rotary inertial thermodynamiccompressor with multiple branches facilitates the construction of asystem in which the same compressor is capable of providing a smallamount of flow into a very high back pressure and/or a large amount offlow into a low back pressure. For instance, one of the branches in amultiple branch system can have a large number of rotary inertialthermodynamic compression stages cascaded. This allows it to produce avery high pressure at its delivery outlet. This would be deliveredthrough an appropriate check valve into the output plenum. In the faceof such back pressure, the other branches in the system would have zeroflow. Flow would not go backwards through them because of their checkvalves. The other branches would not cause an appreciable thermodynamicloss, because with essentially negligible flow within them, the fluid inthem would absorb essentially negligible amounts of heat from their heatexchangers. The thermodynamic and/or mechanical impedance of thecascaded branch of the compression system can be chosen high enough sothat when there is a large flow at low pressure, the fraction of theworking fluid passing through the cascaded assembly is small compared tothe fraction of working fluid passing through the other parallelbranches. In that case, the amount of heat absorbed from the heatexchangers in the high compression cascaded branch can also be madesmall, so that heat absorbed by this branch causes only a smallthermodynamic loss.

THERMODYNAMIC COMPRESSOR WITH IMPEDANCE-INDUCED COMPRESSION

For a number of applications it is possible to construct a rotaryinertial thermodynamic compressor in which the conduits extending awayfrom the axis of rotation and those returning towards the axis ofrotation operate at essentially the same temperature. During operation,differences in temperature in the working fluid necessary to providedifferences in density, which, in turn, cause compression, arise fromthe differences in the thermodynamic impedances through which heat iscoupled into and out of the working fluid in the various conduitsegments.

In FIG. 24 is shown a compressor 549 of the type described in thepreceeding paragraph. Flow in the forward direction is represented bythe arrow 550. A system of this type is capable of pumping a workingfluid in either direction. For purposes of discussion, it will beassumed that working fluid entering the system for either direction offlow is at a temperature substantially below that of a heat source 557.Cool working fluid enters device 549 at inlet 551, proceeds radiallyoutward through conduit segment 552, radially inwardly through conduitsegment 553, which is in thermal contact with conduit segment 552, andleaves the system through outlet 556. Conduit segment 553 includes heatexchange means 554 and adiabatic expansion region 555. In conduitsegment 552 and adiabatic expansion region 555 there is a relativelyhigh thermodynamic impedance for transfer of thermal energy from theworking fluid to the walls of the system, or from the walls of thesystem to the working fluid. When the working fluid is moving with verylow flow velocity, this heat transfer is adequate to insure that theworking fluid be essentially in thermal equilibrium with itsenvironment. This provides for an isothermal compression and expansion.In that case, the compressor 549 gives very little compression. This isrepresented graphically in FIG. 25 by curve portion 559. In the regionnear zero flow, the compression available from this system, in eitherthe forward or reverse direction, is very small. As the rate of flowincreases in the forward direction, the effectiveness of heat transferin conduit segment 552 and adiabatic expansion region 555 issufficiently small so that the compression of working fluid in conduitsegment 552 and its expansion in region 555 become essentiallyadiabatic. Under such circumstances, the behavior of the compressor 549becomes essentially that of the compressor shown in FIG. 5. Workingfluid at a relatively low temperature enters through inlet 551,experiences adiabatic compression on progressing radially outwardly inconduit segment 552, expands relatively isothermally in heat exchangemeans 554 within conduit segment 553, absorbing heat from heat source557, expands essentially adiabatically in expansion region 555, andleaves the system at outlet 556. In the absence of other mechanisms forstabilizing the flow of working fluid within rotary inertialthermodynamic compressor 558, it is necessary to operate on a portion ofthe curve 559 in FIG. 25 for which the slope of the tangent line 561 ispositive. Recalling the sign convention of P as being the pressure atthe inlet minus the pressure at the outlet, quadrants 2 and 4 in FIG. 25represent compression, respectively, in the reverse and forward flowdirections. For forward flows greater than the value represented bydotted line 560, a small increase in the amount of flow results in adecrease in the driving compression produced by the compressor. This, inturn, allows the amount of flow to return to its initial value.Similarly, a decrease in flow below the chosen operating line, but notless than line 560, results in an increase in the driving pressure,restoring the flow to its original rate. In this way the operation ofthe system is stabilized. Similarly, flow in the reverse direction atmagnitude greater than represented by dotted line 562 leads to animpedance, for small fluctuations, which also has positive slope.Operating points further to the left of dotted line 562 and lying in thesecond quadrant represent stable compression for reverse flow.

One advantageous feature of the compressor 549 is that its operation isdependent upon the differences in thermodynamic impedance in conduitsections 552 and 553, which, for purposes of discussion, can be regardedas arising from heat-exchange means 554 located within conduit segment553 and the properties of heat source 557 to which it isthermodynamically coupled.

GASEOUS-LIQUID THERMODYNAMIC DEVICES

All of the rotary inertial thermodynamic devices discussed thus farutilize working fluids whose state does not change within the device.For a number of applications it is desirable to use devices within whichthe working fluid changes from a gas to a liquid or a liquid to a gas;see, for example, my U.S. Pat. No. 3,470,704, FIGS. 4 and 8, and myabove-identified U.S. Pat. No. 3,808,828. In general, operation of thesystems to be discussed below will depend upon changes of a gaseousworking fluid into liquid working fluid, as by evaporation andcondensation, and/or the absorption and evolution of a gaseous workingfluid by a liquid working fluid.

FIG. 26 shows one form of condensation and evaporation rotary inertialthermodynamic cooling device. The forward direction of flow is indicatedby arrow 579. Pressurized gas is introduced into the system through aninlet 580 and flows into a condensation chamber 581. Condensationchamber 581 is equipped with heat exchange means (not shown) having athermodynamic impedance Z44 for coupling heat from working fluid withinchamber 581 to the external environment. The gas condenses in chamber581 and loses its heat of condensation through the impedance Z44. Thecondensed liquid 586 accumulates against outer wall 583 of chamber 581under the influence of rotary inertial forces, and drains into a rotaryinertial trap 585 having a mechanical impedance Z45. The liquid proceedsthrough the trap 585 into evaporation chamber 591 where it evaporates ata reduced pressure, extracting from its environment the heat ofvaporization necessary for this evaporation through an impedance Z46.This impedance Z46 includes the impedance of the source from which heatis extracted and all intermediate heat exchange means. Gaseous-formworking fluid proceeds radially inwardly through region 589 ofevaporation chamber 591 and leaves the system through an outlet 590.

For operation as a refrigerator, the gas at inlet 580 has a higherpressure than at the outlet 590. The difference in gas pressure betweenchambers 581 and 591 is counterbalanced by a difference R in the radiallocation of surfaces 592 and 593 of the liquid 586. This difference,acted upon by the rotary inertial forces, is utilized to give rise toquite a substantial back-pressure, to provide for the condensation atrelatively high pressure of gas in the chamber 581.

One advantageous feature of the mechanical impedance Z45 of the trap 585is that its value is adjusted automatically to provide exactly theamount of back-pressure necessary to counterbalance the gas pressuresacting upon it, regardless of the variation of flow rate over a widerange, and regardless of the variation of impedances Z44 and Z46 over awide range. It is this self-adjusting feature that makes operation ofthe trap thermodynamically reversible, i.e., at no point is a workingfluid delivered through a mechanical constraint at an appreciabledifference in pressure. The stabilizing effect of this self-adjustingform of mechanical impedance can be seen readily by considering the casein which impedance Z44, through which heat is rejected from condensinggas in chamber 581, and impedance Z46, through which heat ofevaporization is supplied to the evaporating liquid in chamber 591, bothare made relatively large. As these impedances are made larger, for agiven flow, the pressure drop across the whole cooler 594 becomeslarger. The result of this increased pressure drop is that thedifference R between radial locations of surfaces 592 and 593 becomeslarger. However, the gas is not allowed to move freely (bubble) fromchamber 581 to chamber 591 until a very large gas pressure (e.g.,several hundred p.s.i.) is developed. Thus, the trap operatesefffectively over a wide range of operational parameters.

The use of traps such as the trap 585 in rotary inertial thermodynamicsystems is shown in FIGS. 1, 2, 3, 5, 6, 8, 9, 10 and 15 of myabove-identified co-pending patent application. A rotary inertialthermodynamic cooling system has been constructed and successfullytested. It uses a refrigeration section of the type shown in FIG. 26 anda cascaded gaseous rotary inertial thermodynamic compressor of thegeneral form shown in FIGS. 12 and 13.

The rotary inertial thermodynamic device 594 is thermodynamicallyreversible, and therefore can be operated as a compressor. In thismodification of the operation of the FIG. 26 device, working fluidenters the rotary inertial thermodynamic compressor device at inlet 580,as before. The fluid proceeds in the direction indicated by arrows 579into chamber 581. The working fluid entering the system may be in theform of either a liquid or a gas. If it is in the form of a liquid, thenimpedance Z44 is not important to the operation of the device. Heat isadded from a heat source (not shown) to the liquid at surface 587 ofchamber 591 to evaporate the liquid in chamber 591. The inner surface604 of the liquid, in the case where the chamber 581 is not entirelyfilled with liquid, is indicated in dashed outline. For operation as acompressor, this inner surface 604 is radially inward from the surface605 of the liquid in chamber 591. The difference in the radial distancesof these two surfaces from axis 1 is designated R₁. From chamber 581liquid flows through the trap 585 and thence to chamber 591, wherein itevaporates at a pressure greater than that in chamber 581. Vapor formworking fluid proceeds radially inward within chamber 591, and leavesthe system at outlet port 590. The inlet 580 and outlet 590 do not haveto be on the axis 1.

Careful examination of the operation of device 594 shows that impedanceZ45 is distributed throughout the system, in the sense that it dependsupon the levels 604 and 605 to which the liquid working fluid approachesaxis 1 in chambers 581 and 591.

Operation of the device 594 as a compressor is illustrated in FIG. 27.Using the previous convention that ΔP represents pressure at inlet minuspressure at outlet, two different conditions have been shown. Curve 612describes the case in which impedance Z46, the impedance of the heattransfer into chamber 591, is relatively large. Curve 613 describes thecase in which Z46 is relatively small. Curve 614, representing reverseflow, applies to both cases.

In the case in which the impedance Z46 is relatively small, thetemperature of working fluid evaporating in chamber 591 is essentiallythe temperature of the heat source, and the temperature does notdecrease appreciably as the amount of heat flowing increases. The vaporpressure of the liquid working fluid depends upon its temperature.Holding the temperature relatively constant ensures that the vaporpressure will be relatively constant. This gives rise to the relativelyflat relationship between pressure and flow, shown graphically by linesegment 613. Therefore, if the outlet of device 594 is blocked, thepressure in chamber 591 does not increase to a high value; it increasesonly until the delivery pressure reaches the vapor pressure of theliquid at the temperature of the heat source, or, until evaporation ofworking fluid within chamber 591 completely empties chamber 591, so thatliquid is no longer exposed to the heat source through the impedanceZ46. In FIG. 27 line segment 613 represents an operating point at whichthe temperature of the heat source is not high enough to cause a vaporpressure in the chamber 591 sufficient to empty chamber 591.

In the case where Z46 is relatively large, as represented graphically inFIG. 27 by line segment 612, as the flow rate increases, the temperatureof the working fluid during evaporation in chamber 591 decreases. Thisis because the more rapidly the working fluid flows, the more heat flowis required from the heat source in order to evaporate working fluid inchamber 591. Therefore, the temperature drop across Z46 is larger. Asthe temperature of the evaporating working fluid drops with increasingflow, so also does vapor pressure available to provide compression. Itis for this reason that there is a relatively sharp drop in compressionwith increasing flow of working fluid. As the flow rate decreases, thetemperature of the evaporating working fluid increases. This increasedtemperature gives rise to an increased vapor pressure with acorresponding increase of delivery pressure available at the outlet.This process continues until the pressure becomes so great that workingfluid in liquid form is completely cleared from chamber 591, back intotrap 585. At that point, liquid working fluid only enters chamber 591 asrapidly as gaseous form working fluid is allowed to be delivered throughoutlet 590. In the latter mode of operation, the pressure delivered bythe compressor 594 becomes essentially independent of the rate of flowof working fluid therein. This is shown graphically in FIG. 27 by linesegment 615. From line segments 613, and 612 with 615, we see that thedevice is not capable of producing sufficient forward compression toempty its trap 585 and thereby render itself relatively susceptible toreverse flow.

Were we to connect a device of the type shown in FIG. 26 to a mechanismwhich pushes gas through it in the reverse direction, it would benecessary for that mechanism to produce a back-pressure sufficient toovercome the pressure created by the difference in radial surfacepositions between the outermost point of the inner wall 582 of trap 585and the innermost point to which working fluid would reach in chamber581, equal to the maximum forward compression plus a pressure gap markedG in FIG. 27. With such a back-pressure, the gas would bubble backthrough trap 585 and chamber 581. This is illustrated by line segment614 in FIG. 27, which shows that, with reverse flow of this form, thereverse pressure does not depend strongly on the amount of flow. This isbecause the mechanical impedance due to friction is presumed to berelatively small.

The pressure gap G can be relatively large. This serves effectively tostabilize operation of the device. A device of this type isunconditionally stable in the sense previously defined. From theforegoing discussion of the stability of rotary inertial thermodynamiccompressors containing multiple branches operating in parallel, it isclear that a flow-pressure relationship of the type shown in FIG. 27makes the device 594 especially suitable for use in parallelconfiguration.

The device 594 offers a particularly clear example of a relationshipbetween internal flow of a working fluid within a rotary inertialthermodynamic device, and external and internal thermodynamic impedancesthrough which heat is transferred to or from the working fluid. Thedifferences between line segment 613, and line segment 612 and 615 takentogether, arise without need for changes in the internal structure ofthe device, but rather just by changing the thermodynamic impedanceswith which it is coupled to a heat source. Clearly, a rotary inertialthermodynamic system including a device of this form should be analyzedby treating the device as part of a larger system, including itsinternal impedances and also the external impedances of the environmentwith which it interacts. This is true, whether the device is a part of asealed-conduit device, all of which rotates as a single unit, or is partof a hybrid system--hybrid in the sense that part of it rotates and partof it is stationary, with couplings through rotating seals between therotating part and the stationary part wherever needed, or in the sensethat parts rotating with different velocities are co-joined for fluidflow.

From the previous discussions of stability of rotary inertialthermodynamic compressors containing multiple branches connected inparallel, it can be seen that the use of a device as shown in FIG. 26 ineach branch, possibly in combination with other compression means in thebranch, can serve to stabilize the composite compressor. If desired, itis possible to utilize various impedance means in combination to rendereach of the branches unconditionally stable; device 594 is effective assuch a means. It also is possible to utilize various different types ofcompression devices in the various branches, i.e., it is not necessaryfor all of them to utilize the same internal geometry or constructiontechniques.

The angular velocity with which the device shown in FIG. 26 is rotatedaffects the maximum back pressure into which the device can deliverworking fluid. For rotary inertial thermodynamic devices of the typeshown in FIG. 26, the angular velocity at which the device is rotatedusually strongly affects the thermodynamic and mechanical impedances.

FOREPUMP FOR STABILIZATION

Rotary inertial thermodynamic compressors of the type shown in FIG. 26require a certain minimum input gas pressure for proper operation,because liquid must be present within the trap 585. If the available gassource cannot meet the requirements, a device 723 of the type shown inFIG. 28 may be utilized. This is one example of a general class ofsystems utilizing part of the compressed gaseous working fluid deliveredby the rotary inertial thermodynamic compressor to actuate a forepump orother secondary pump, in this case, raising the pressure of the gasavailable at the intake to a high enough value to allow proper orefficient operation of a compressor.

The device 723 has an inlet 707 which receives gas flowing in thedirection designated by arrow 706. 708 generally designates a forepump,in this case containing an expansion nozzle 709 and a diffuser 710,which together serve as a jet pump to drive gaseous working fluid into acondensation chamber 711 at a higher pressure than is available at inlet707. Chamber 711 contains intermediate pressure gas 713, whichcondenses, delivering its heat of condensation to an externalenvironment through thermodynamic impedance Z719. The condensed liquid716 collects at the outermost portion of chamber 711 and drains into arotary inertial trap 715, and flows in the direction of arrow 725 intoan evaporation chamber 718. The difference in liquid levels 712 and 717in conduit segment 715 and chamber 718, respectively, acted upon bycentrifugal forces, provides the necessary driving pressure utilized inproducing high-pressure gas for delivery at the outlet 726 of the device723. The heat of vaporization required to evaporate the liquid inchamber 718 is supplied by a heat source 724 through a thermodynamicimpedance Z720. The high-pressure vapor, designated 714, flows radiallyinwardly through conduit segment 727 and divides into two streams, oneleaving at the outlet in the direction designated by arrow 712, and theother returning through a high-pressure conduit 722 to actuate theforepump 708. Further details of such a forepump are given in myabove-identified U.S. Pat. No. 3,808,828.

The forepump, shown in the form of a jet pump, supplies sufficientworking fluid so that the system never turns off at its intake oroutlet. Even if the amount of working fluid entering the system isessentially zero, if it is operating into a back pressure at outlet 726,and if there is a pressure difference sufficient to maintain adequateflow in jet nozzle 709, the input to the liquid and gas rotary inertialthermodynamic compressor will be sufficient to produce the necessarycondensation in chamber 711 and keep that portion of the systemoperating. For this reason, a device of this type is not susceptible toflow reversal merely be reduction of intake pressure. The forepump meansrenders the device stable over a wider range of flow input impedance. Atthe same time, it raises the working fluid pressure in condensor chamber711, allowing condensation to occur at a higher temperature. This allowsthe heat of condensation to be rejected through a higher thermodynamicimpedance, without interfering with stable operation of the device, thanmight otherwise be the case.

All of the rotary inertial thermodynamic gaseous compressors previouslydiscussed operate on a ratio; that is, the input pressure was assumedfixed, and the difference in pressure between output and input was thenevaluated.

In place of the rotary inertial compressor in FIG. 28 of the typeappearing in FIG. 26, one can use a gaseous compressor such as in FIGS.5 or 10. Forepump means 708 then serves to increase the input pressureto the inlet of the gaseous compressor which, by the nature of itsoperation, multiplies its input pressure. Use of the forepump meansreduces the input impedance of the composite device. Also, flow throughthe forepump jet can prevent flow through the compressor from enteringthe unstable region near zero flow. In both these ways, the forepump canserve to stabilize operation of a rotary inertial thermodynamiccompressor. it also serves to reduce the number of stages required for agiven compression ratio and/or to increase the maximum compression ratioavailable from the composite system. A composite device of this tupe canbe made which will not be forced into reverse flow by an arbitrarilylarge source or impedance.

As was discussed in greater detail earlier, the operation of the systemsdescribed herein, utilizing a flow of gas in a rotor and depending upontemperature-dependent differences in density in that gas for theirthermodynamic effects, depends upon the ratio of inlet and outletpressures. For simplicity in discussing these effects, the ratio isdiscussed in terms of the pressure difference across the device,assuming that either the inlet or the outlet pressure is held constant.The physical reasons for the dependence upon ratio of pressure ratherthan pressure differences, and the way in which this can be taken intoaccount, was, discussed in detail. This should be borne in mind withrespect to the graphs herein showing pressure difference versus flow ingaseous working fluid devices. In addition, in general, the effects ofchanging the angular velocity of rotation have not been discussed inexplaining the stability and instability of flows within the rotaryinertial thermodynamic devices. The reason for this is that thestability or instability of the flows has essentially the samedependence on pressures and thermodynamic impedances at various angularvelocities, except for scale factors which are dependent upon theangular velocity. The essential features required to understand theprinciples for stabilizing these systems can be set forth and understoodby considering systems rotating with constant angular velocity. Ways inwhich variations in angular velocity can be utilized to alter impedanceshave as their physical basis the dependence of centrifugal and coriolisforces on angular velocity.

Basic to the operation of rotary inertial thermodynamic compressors isthe availability of thermal energy within the rotating system.Associated with the ways in which this thermal energy can be madeavailable are characteristic thermodynamic impedances which, in turn,influence the behavior of the system, of which this rotary inertialthermodynamic device is a component. The mechanisms by which thermalenergy are made available within the rotating device can be combinedwith the mechanisms which serve to provide the necessary rotation. Inthe calculation of Carnot efficiency for a compressor viewed as a heatengine, the overall performance is more sensitive to fluctuations in theheat rejection temperature than in the heat absorption temperature. Thisis because the same change in temperature represents a larger fractionof the overall temperature, because the temperature at which the heat isrejected is smaller than the temperature at which the heat is absorbed.Therefore, it is desirable to keep the impedance for the rejection ofheat as small as feasible. For most of the operating points which wouldoccur in systems of this type, the temperature for heat rejection issufficiently low so that radiant heat transport is not an adequate meansfor removing the heat present. Also, typically, thermal conduction isnot an efficient means for transferring heat out of a rotating device.For these reasons, the mechanism of heat transport used for removingheat from the rotating device is typically convective, that is, the heatis transported by the transport of some fluid. In a single-stage rotaryinertial thermodynamic gaseous compressor, this transport of heat occursby the transfer of working fluid from the device performing thecompression. If this transfer is to a stationary component in a hybridsystem, the transfer of heat from the rotating device has occurred bythe transfer of this working fluid. In the event that the compressor ispart of a larger rotary inertial thermodynamic device, all of whichrotates together, the heat rejection occurs by heat exchange throughsome surfaces to some moving medium. In the location in which the heatrejection is required, a gaseous compressor is different from a gaseouscooling system. In a gaseous compressor, the heat exchange for rejectionoccurs relatively near the axis, allowing a larger coolant flow withrelatively small momentum transfer. In comparison, a cooling devicerequires heat transfer at points relatively far from the axis ofrotation, having associated therewith higher tangential velocities andlarger momentum transfer per unit of heat transfer to a coolant. In thefollowing sections, I will discuss ways in which heat can be transferredinto and out of a rotary inertial thermodynamic device and discuss thecharacteristics of the thermodynamic impedances associated with thevarious means of heat transfer. This is not a complete enumeration ofmeans of transfer, but rather a representative list serving tocharacterize the impedance and the dependence of the impedance on thephysical form of heat transfer.

HEAT SOURCES

It is to be understood that, where required by the processes occurringtherein, rotary inertial devices are provided with heating and heatrejection means. These means can be used in many combinations. Forsimplicity, heating and heat rejection means are discussed separately.In the figures, one or more means may appear in the same diagram, and,for simplicity, occasionally heating or heat rejection means may beomitted from a diagram intended to illustrate another means, without anyimplication about the necessity of omitted means.

RADIANT HEAT SOURCES

In FIG. 29, 1 is the axis of rotation, 761 generally designates theradiant energy source, e.g., a lamp 750 with reflector 760. 764 is therotary inertial thermodynamic device to be heated, and 762 is thesurface of device 764 upon which radiant energy impinges to produceheating. 763 is an optically transparent, or nearly transparent, body ofinsulating material which allows radiant transfer of heat to surface 762while reducing heat loss by convection and conduction to the surroundingmedium. The radiant energy source 761 can either be an artificial sourceof radiant energy or a natural source, such as the sun. With suitableuse of an optical system, not shown, solar energy can be caused toimpinge upon and heat the surface 762. This heat transfer technique canalso work in a vacuum. Portions of the device can be heated differentlyby presenting a surface with different absorbtivity to the radiant flux.

INTERNAL HEAT SOURCES

Another form of heating is provided by a heat source which generates theheat within the rotating device itself without external coupling to theenvironment. Among such sources are radioisotope sources which releasethermal energy by their decay; nuclear fission fuel elements, which canbe utilized in part of a reactor to provide heat to the mediumsurrounding them without appreciable transfer of momentum; fullycontained chemical reactions proceeding within the rotating device; and,potentially, fusion to release energy from nuclei. With these forms ofheat production within the rotating device itself, heat can be deliveredwherever it is needed for maximum thermodynamic efficiency. Inparticular, heat exchangers buried deep within a thermally insulatingstructure can be heated in this way so as to insure that essentially allof the heat introduced is utilized in the thermodynamic processes in therotating device.

INDUCTIVE HEAT SOURCES

Electrically conductive components of a rotary inertial thermodynamicdevice with suitable electrical resistance can be heated byelectromagnetic induction. As in the case of heat generation from energysources within the rotary device, this also allows selective heating ofcomponents of the device buried deep within insulating members.

The necessary time dependent magnetic field required for electromagneticinduction can be produced in several ways. One way is to rotate thecomponents of the rotary system through a stationary magnetic field withspatial dependence of the field. The induced by the passage of thecomponents through the magnetic field is then a mechanism by whichmechanical shaft work is converted to heating of the buried components.Alternatively, the electromagnetic field can be generated by varying amagnetic field with a characteristic direction of rotation, as isconventionally done in a polyphase motor. This rotating magnetic fieldcan serve two purposes. It can heat the heat transfer means within therotary inertial thermodynamic device, while the drag between thecomponents so heated and the rotating magnetic field rotates the device.

The foregoing arrangement is illustrated in FIG. 30, in which 765 is therotary inertial thermodynamic device, in which are buried heat exchangemeans 766 which have the appropriate electrical conductive impedance andheat transfer properties. For example, exchangers 766 might be simplestrips of conducting material, or sintered porous metal plugs with manyfine passageways. 767 is an electromagnet assembly having a suitablecore 771, and a winding 772 connected to a suitable alternating currentpower source 773. A multiplicity of such magnetic elements can beutilized. 768 denotes generally a permanent magnet 769 and pole pieces770. A shaft 771 is mounted on bearings (not shown) and is used tosupport the device 765 for rotation about an axis of rotation 1. In thisarrangement, the rotor serves as the rotor of an alternating currentmotor. Additional heating can be produced within this rotor by theutilization of the stationary magnetic drag field produced by one ormore optional stationary magnet assemblies 768. The amount of torqueproduced by the electromagnet assembly or assemblies 767, and the amountof heating produced thereby, can be separately controlled by controllingthe frequency of the power source 773, or by the use of drag fields, orby controlling the phase of power to several electromagnetic assemblies767. These electromagnetic heating techniques offer a way of simplifyingthe drive means for rotary inertial thermodynamic devices. These meansfor heating and rotating operate in many kinds of environments,including a vacuum.

DIELECTRIC HEAT SOURCES

Dielectric heating also can be used to create heating within therotating device. High-frequency magnetic hysteresis heating also can beused. A dielectric heating arrangement is shown schematically in dottedlines in FIG. 30. Plates 775 are positioned on opposite sides of therotary device 765. The plates are connected to a source 776 whichsupplies an appropriate high-frequency alternating voltage across theplates. The plates are positioned so as to provide a rapidly alternatingelectric field which heats a dielectric material in the device 765. Theplates are positioned, of course, so that only the desired portions ofthe rotary device 765 are heated. Portions to be heated are preferablymade of a material with a large loss tangent the field frequency, whileother parts are made of a relatively low-loss dielectric material. Forexample, ferroelectric ceramics, such as barium titanates, are availablewhich can be made to have an adequately large loss-tangent. "Mylar",polystyrene, and many other plastics, and many other ceramics have lowloss-tangents. Some low loss-tangent materials, for example, berylliumoxide, also posses high thermal conductivity, and are suitable forconductive heat transfer. Both dielectric and induction heating areshown in the same figure for simplicity. Typically, they would be usedseparately. Means for heat rejection (not shown) such as, for example,those shown in FIGS. 34 and 35, can be utilized if required by thethermodynamic process occurring within the rotor. Some devices, such assingle-stage gaseous compressors, can reject heat with working fluidleaving the device, without special provision for separate rejection ofheat.

INTERNAL FUEL BURNING

Another method for heating is to burn fuel within the rotating device.FIG. 31 shows an arrangement for this purpose. 777 designates generallya rotary inertial thermodynamic device to be heated. An intake for airis at 778, and a fuel inlet is at 799. The fuel-air mixture passesoutwardly through conduit means 783 past combustion stabilizing means780 (e.g., screens) into combustion region 782, and thence out of therotating device through nozzles 781. Alternatively, the combustionproducts can be returned nearer to the axis of rotation and dischargedfrom the rotating device through appropriate conduit means, not shown.Suitable ignition means, not shown, can consist of a small spark plug orglow plug, with, for example, piezoelectric actuators for a spark plug.The jet nozzles 781 are oriented so that their exhausts are in the samedirection, and contribute reaction torque to produce or augment rotationin the device 777, as is explained more fully in my above-identifiedco-pending application.

ELECTRON BEAM HEATING

Yet another technique for transferring heat into a rotary inertialthermodynamic device is bombardment with an electron beam. In FIG. 32 isillustrated a vacuum device utilizing electron bombardment for heating arotary inertial thermodynamic device 805 secured to a shaft 802. 804 isa stationary vacuum chamber surrounding the device 805, and 803 aresuitable rotary seals. The shaft 802 and the device 805 rotate about theaxis of rotation 1, and the seals 803 maintain the vacuum in the chamber804. A suitable electron gun 806 is utilized for the bombardment of thedevice 805 in order to produce heating at selected locations therein.Electron gun means 806 operates from power supply 807. The details ofthe electron bombardment device are not shown explicitly. Many devicesare known, especially in the art of thin film evaporation and depositionin vacuum, where they are utilized extensively for heating evaporationsources. Many types of seals are known which can be utilized for seal803. Especially useful seals are those using ferro-magnetic fluidsuspensions. The evacuation means for vacuum chamber 804 is not shown.

VAPOR (STEAM) HEATING

Steam, or other actuating vapor, often is available as a source ofthermal energy. It is feasible to both heat and spin a rotary inertialthermodynamic device utilizing a vapor as an actuating fluid. Forspecificity, consider water vapor (steam). In FIG. 45 is shown anotherembodiment in which the rotary inertial thermodynamic device 811 isshown with vanes 814, and a shroud 812. Vapor is directed obliquelyagainst the vanes 814 through a nozzle 813. The vanes 814 serve both toaugment the reaction of the vapor against the rotating member and totransfer heat therefrom into the rotating device 811. Condensate iscollected in the shroud 812 and leaves through a drain 815. Bycontrolling the angle with which the vapor jet causes vapor to impingeon blades 814, it is possible to control independently the amount ofrotational torque produced and the amount of heating produced. Thedevice heated can be part of a larger rotating assembly containing otherrotary thermodynamic devices lying outside of the shroud 804.

Radiant heat transfer, electromagnetic induction and hysteresis,dielectric heating, and electron bombardment readily can be used forselective heating of portions of a rotary inertial thermodynamic device,so that the heat can be applied to selected regions in order toindependently control processes occurring within the device. Suchregions can be located across an entire surface of the device, includingboth radial and angular variations in position. Variations in heating oflocations about the axis of rotation can be accomplished by modulationof the intensity of the heat source. For example, the electron beamintensity can be modulated. A light source can be modulated inintensity, or operated as a succession of bright flashes using the sametechnique as is used with stroboscopic lamps. Electromagnetic inductionand hysteresis, and dielectric heating can be modulated both as tofrequency and amplitude. In this way, it is possible to controlseparately the temperatures of various parts.

THERMODYNAMIC VALVES

It also is possible to use gaseous compressors as valves, by adjustingthe pressure differences which can appear across them, or to fill andempty traps so as to control flow. Localized heating can be used tocontrol the impedances of such traps.

In FIG. 33 is illustrated schematically a simple valve mechanism,utilizing a chamber 817 containing a liquid 818. The chamber has anoutlet to a bellows 820. The chamber 817 is in thermal contact with thesurface 819 to which heat can be transferred selectively. Localized heatenergy is supplied to surface 819 from outside in a suitably modulatedfashion. The bellows receives vapor from the chamber 820 and operates avalve 821. All of the elements 817, 818, 820 and 821 are inside of androtate with the device 816, which can be of any of a wide variety offorms. Device 816 rotates about axis of rotation 1. For example, amultibranch and/or multistage compressor can have branches and/orcascaded stages selectively valved in this way to allow efficientoperation at reduced capacity, e.g., in a large industrial power plant.

In general, many of the forms of rotary inertial thermodynamic deviceswhich can produce or sustain a pressure difference across their intakesand outlets can be utilized in conjunction with such selectiveapplication of heat to provide means for controlling flow or flowswithin a rotary inertial thermodynamic system.

In many cases it is possible to have a working fluid transport the heatto be rejected by a rotary inertial thermodynamic compressor from therotating device. In those cases, no special provision need be made forrejecting heat. However, in cascaded gaseous compressors, in absorptioncycle devices with closed cycles for the absorbent fluid, and in manyother forms of rotary inertial thermodynamic device, it is necessary toreject heat from a rotating member into its environment. Often, it isdesirable that the amount of mechanical energy lost from the system inperforming such heat transfer be minimized. In some cases it is possibleto use that energy which is consumed from the mechanical rotation of theshaft to do some form of useful work in an external system. Forinstance, the coolant can be circulated by means of an impeller systemrotating with the rotary inertial thermodynamic device. Quite generally,there are many system configurations in which the rotating member of thesystem can be caused to rotate by its environment, and/or can be used tomove parts of its environment. For instance, as has been describedabove, a rotary inertial thermodynamic device might be spun by steam andheated by it at the same time. In turn, the device might be cooled by aflow of fluid, e.g. water, which the device creates by its rotarymotion.

INTERNAL LIQUID COOLING

The most efficient location for conveyance of heat from a rotatingdevice by means of heat exchange with an external fluid is at the hub.At the hub, the tangential velocities of the rotating members are thesmallest. Within the rotating device, heat can readily be transportedfrom a region internal to the device, from which it is being rejected bya thermodynamic process occurring therein, to the hub. In many cases, anefficient way to do this is to utilize evaporative transfer. In FIG. 34is shown schematically a device utilizing such transfer to cool aninternal surface 837 which is in a region in which a thermodynamicprocess occurring within a rotary device is required to reject heat.

In FIG. 34, 1 is the axis of rotation, 830 designates a rotary inertialthermodynamic device within which is shown schematically a heattransport mechanism comprising surface 837, volatile liquid 836, conduitmeans 838, chambers 841 and 839, and heat rejection surface 835.Operation of this heat transport means is by absorption of heat at 837,rejected by some process (through an impedance) into the fluid 836, asindicated by the arrow 843. The fluid 836, absorbing this heat, iscaused to volatilize. The vapor thus formed proceeds into and throughconduit segment 838. Upon reaching chamber 839 it contacts surface 835,condensing thereon, to deliver its heat of vaporization to the surface835. Liquid formed by this condensation flows back through conduit 838to return to the pool of liquid 836 to complete the cycle and be readyto absorb heat again from surface 837.

Although it is not necessary to combine the foregoing and the followingsteps in the same device, at the hub 846 in FIG. 34 is shown a means forrejecting the heat at surface 835 into a coolant liquid circulatingwithin the hub. This coolant enters at inlet 831 and leaves at outlet832 in the direction shown by arrows 840. Liquid flows to near the endof the hollow interior of the hub through tube 834, flows outwardly, andreturns through a rotary seal 833 to outlet manifold 845 and outlet 832.In doing so the liquid passes along the inner surface of hub 846, whichis thereby efficiently cooled and is available as a surface to whichmore heat may be rejected.

The direction designated by arrows 840 in FIG. 34 is appropriate forliquid flow. In the event that the coolant is operative in aliquid-to-vapor conversion, whereby it absorbs heat by vaporization, theproper direction for most efficient operation is counter to thatdesignated by arrows 840. In the latter case, there is evaporativecooling within chamber 846. A liquid film standing against the outerwall, of which 835 is a segment, is used to absorb heat, and its vaporis transported from the system to leave at port 831.

OPERATION IN A VACUUM

For some applications, it may be desirable to operate a very high speedrotary inertial thermodynamic device in vacuum. Within such anenvironment one can use radiative heat transport. In FIG. 35 is shown anillustration of such a system. The axis of rotation is 1. 861 is ashaft. 860 are seals. 864 is some mechanism for radiant heating ofrotary inertial thermodynamic device 863 rotating within vacuum chamber862. (in space, no vacuum chamber is required) Evacuation means forvacuum chamber 862 is not shown. Rotary inertial thermodynamic device863 includes internal heat transport means 872 and 873. 873 is utilizedto transport heat from a region where it is absorbed from radiant source864. 872 is used to transport heat to a heat rejection mechanism 866from somewhere internal to the rotary inertial device 863 where suchheat is rejected from some thermodynamic process. On heat rejectiondevice 866 are located a plurality of thin fins 867, interleaved withstationary fins 868 affixed to a heat rejection means 865. Fins 867 arein thermal contact with, and rotate with, the heat rejection device 866.The rate at which energy is radiated from a black surface at 300° kelvinis approximately 0.046 watts / square cm. or approximately 0.01 calories/ square cm. second. By interleaving very thin, closely spaced vanes itis possible to achieve a sufficiently large area of radiating surface inthe vanes 867 from which radiant energy can be transferred to the coolervanes 868. The rate at which energy is radiated from a black surface isproportional to the fourth power of temperature of the surface. Byutilizing cooling mechanism 865 to cool the fins 868 interleaved withrotating fins 867, the amount of energy radiated by fins 868 issubstantially reduced so that an appreciable radiative tansport of heatfrom rotating vanes 867 to stationary vanes 868 can be achieved.

Cooling means 865 in FIG. 35 includes a conduit 869 for conducting acoolant fluid (e.g., water) into a cavity 879, and manifold means 870for collecting fluid returning from the cavity, the direction of flowbeing represented by arrows 871.

For some special-purpose applications the advantages of rotation at veryhigh speeds in a vacuum are greater than the disadvantages of thestructures required for radiative rejection of heat. The rate at whichheat is transported increases so rapidly with increasing temperaturethat, for many applications in which a higher rejection temperature canbe tolerated, such a transport mechanism becomes an acceptable means forrejecting heat from the rotating device 863. Such means for rejectingheat are characterized by a thermodynamic impedance, as are other meansbased on motion or evaporation of a coolant.

HEAT PIPES FOR HEAT TRANSFER

Still referring to FIG. 35, embedded in the rotary inertialthermodynamic device 863 is a heat pipe heat transport means 882,consisting of a chamber 880 with a capillary material 881 within it, andan appropriate amount of a suitable volatile working fluid. The heatpipe 882 is operative to transport heat by evaporation of some workingfluid in contact with surface 883, which is heated by radiant heattransfer means 864, and to transport vapor therefrom to condense anddeliver heat through impedance Z884 to some thermodynamic process, withthe condensate returned to the surface 883 by capillary action in thematerial 881.

In utilizing heat pipes for such heat transport within a rotary inertialthermodynamic device, the augmented acceleration field associated withthe rotation of such a device, and its effect upon the motion of theliquid working fluid utilized within the heat pipe, should be taken intoaccount. The magnitude of the acceleration fields found in rapidlyrotating devices of this type makes it quite difficult for a capillarysystem to transport a liquid form of working fluid radially inwardly byany great distance. However, in devices rotating with relatively lowangular velocities, such capillary and vapor type transport systemsgenerally known as heat pipes are suitable for transporting heat fromone portion of the rotary device to another.

INTERNAL ELECTRICAL HEATING

An additional way for conveying thermal energy into a rotary inertialthermodynamic device is to use a slipring assembly to transferelectrical energy which is then utilized in some appropriate form forproducing heat within the device. In FIG. 36 is shown such a heatingsystem. 1 is the axis of rotation and, 908 is a shaft carrying a rotaryinertial thermodynamic device 909. A pair of sliprings 911 on shaft 908make electrical contact with a pair of brushes 912, which are connectedto a suitable power supply 913. Inside of the rotary device 909 is asuitable electrical energy-to-heat conversion means, such as aresistance heating element 910. This conversion means is connectedelectrically to the sliprings 911. The thermodynamic impedance of thisheat transfer mechanism depends upon the detailed mechanism by whichelectrical energy is converted to thermal energy, (e.g., positive andnegative coefficient thermistor heating elements, metals, etc.) and theproperties of the power supply used to deliver electrical energy to thesystem. The effective thermodynamic impedance of such a heat transfermechanism can be adjusted over a very wide range. The means utilized forconversion of electrical energy to thermal energy can also participatein the operation of the rotary inertial thermodynamic device in otherways. For instance, it can be incorporated as part of a mechanical flowimpedance and thus can have intimate contact with the working fluid.

IMPEDANCES OF FOREGOING HEAT SOURCES AND DRAINS

Heating by means of radiant energy transfer, isotopes, magneticinduction, combustion in a rotating system, electron bombardment andcombinations of these means are characterized typically by a highthermodynamic impedance; that is, the amount of energy delivered to therotating device being heated varies only slightly with the temperatureof the portion of the rotating device receiving the heat. In the case ofsteam or other vapor heating, the effective thermodynamic impedance ofthe source is much smaller. In this case, the temperature of the portionof the rotating device receiving heat is very nearly that of thecondensation of the vapor at the pressure involved. A decrease in thetemperature of the region at which condensation is occurring results ina substantial increase in the amount of condensation there. For thisreason, the thermodynamic impedance of such a vapor heat transferprocess depends upon the mechanical impedance by which the vapor issupplied to, and by which spent vapor and condensate are removed from,the surfaces receiving heat.

Cooling of a rotating device by convection and evaporation are alsocharacterized by thermodynamic impedances, typically substantially lowerthan those associated with the high-impedance heating techniquesmentioned above. Of these, typically evaporation techniques havecharacteristically the lowest impedance, again because of the dependenceof the evaporation temperature upon ambient pressure. In the case ofevaporative cooling, as in heating, the detailed thermodynamicimpedances associated therewith depend upon the mechanical impedances bywhich liquid is fed to and vapor removed from the region whereevaporation occurs.

Heat rejection through a radiative heat transport mechanism of the typediscussed in connection with FIG. 35 has a characteristic thermodynamicimpedance intermediate between those impedances associated withmechanical fluid flows and vapor condensation and evaporation, and thoseassociated with radiant heating and isotope heating. Isotope heatingprovides the highest impedance of all of the types discussed above.

IMPEDANCE CONTROL FOR HEAT SOURCES AND DRAINS

It is possible to use a temperature-sensing process with feedback tocontrol the effective thermodynamic impedance by varying the propertiesof the heat source in order to render either the rate of flow of heat orthe temperature of the receiving surface nearly constant. If the rate offlow of heat is held essentially constant, then the heat source has beenstabilized in a very high thermodynamic impedance mode. If thetemperature of the receiving surface or of any point selected within thethermodynamic system is held constant, then the total thermodynamicimpedance from the heat source to that point becomes effectively verysmall.

In a similar fashion, feedback can be used to change the effectiveimpedance of the heat rejection means. For instance, the amount of flowof coolant past a heat rejection surface can be controlled so as tomaintain the temperature of that surface essentially constant, or so asto maintain the rate at which heat is removed by the coolant essentiallyconstant. These two cases correspond, respectively, to an extremely loweffective thermodynamic impedance and an extremely high effectiveimpedance. Of course, feedback can be used to obtain impedancesintermediate in value between these extremes.

The transfer of heat into or out of a rotating device can be made todepend upon some property of the materials used. For example, in thecase where heat transfer elements deep within an insulating rotaryinertial thermodynamic device are heated by electromagnetic induction,the temperature of such elements can be maintained essentially constantby utilizing the property of ferromagnetic materials that above theircurie temperatures they cease to be ferromagnetic. In this way, theamount of electromagnetic induction power drawn from an oscillatingelectromagnetic field can be regulated by the element which is drawingthat power itself. As its temperature passes above the curietemperature, the amount of power which it draws from the oscillatingelectromagnetic field decreases substantially. Similarly, when itstemperature drops below the curie temperature, the amount of power drawnfrom the field increases substantially. In this way, it serves as itsown temperature regulator. A corresponding effect is seen in somedielectric materials, (e.g., ferroelectric ceramics) and might beutilized to regulate their temperature in an oscillating electric field.

Another way in which internal regulation can be achieved is by means ofa device of the type discussed in connection with FIG. 34, in which avapor transport system is utilized to transfer heat. The properties ofsuch a transport system depend strongly upon the temperature. As thetemperature of surface 837 in FIG. 34 increases, the vapor pressureavailable to drive vapor form working fluid through conduit 838increases, and, therefore, the capacity of this mechanism to transportheat to surface 835, at which it is rejected, increases. By choosing theliquid 836 appropriately, it is possible to make this dependence ofvapor pressure upon temperature of surface 837 effective to limit thetemperature of a process rejecting heat into surface 837. INTERNALCHEMICAL REACTION: COMBUSTION

Thermal energy also can be introduced into a working fluid within arotary inertial thermodynamic device by having the energy appeardirectly within the working fluid itself, rather than by using someexternal means to couple heat energy into the fluid. For example, aradiation absorbtive, or partially absorbtive, fluid, can be exposed toradiation (electromagnetic, particulate, etc.) which it absorbs, therebytransferring the radiation energy directly into the fluid. Or, theworking fluid can be of such a nature as can support an internalenergy-releasing reaction, for instance, a mixture of fuel and oxidizer.

FIG. 41 shows a rotary inertial thermodynamic gaseous compressorutilizing such a working fluid which can support combustion. Workingfluid is introduced in the direction designated by arrow 1010 at aninlet 1011. It proceeds radially outwardly through conduit segment 1012,within which is experiences essentially adiabatic compression. Reactionstabilizing means 1013, e.g., a screen, or catalyst, stabilizes aheat-producing chemical reaction occurring in reaction zone 1014, withinconduit segment 1016. After this reaction zone the working fluidproceeds radially inward through adiabatic expansion region 1015, toleave the device at outlet 1017. Optionally, a portion of thehigh-pressure working fluid can be bled from the system to operate sometangential jet, designated 1018, or all of the working fluid can bereturned to the axis of rotation within conduit segment 1016. It is tobe understood that inlet 1011 and outlet 1017 do not have to be on theaxis of rotation, and that this rotary inertial thermodynamic device canbe part of a system including other portions which rotate or arestationary.

INTERNAL NUCLEAR REACTION

FIG. 42 shows a system utilizing a nuclear reaction to produce heatwithin a gaseous working fluid. Flow of working fluid is in thedirection designated by arrow 1019, entering at inlet 1024, progressingradially outwardly through section 1020, within which the working fluidexperiences essentially adiabatic compression, proceeding to a reactionchamber lozl, within which the nuclear reaction occurs, progressingradially inwardly through adiabatic expansion region 1022, and leavingthrough outlet 1023. Again, it is to be understood that inlet 1024 andoutlet 1023 do not have to be located on the axis, and that this devicecan be used in simple or hybrid rotary inertial thermodynamic systems.

An example of a suitable nuclear reaction in reactor 1021 would be oneusing uranium hexafluoride as a working fluid. In the reactor 1021 is aknown moderating structure 1025 for facilitating the reaction. Thereaction would occur within the reactor and not occur elsewhere withinthe system. With certain types of nuclear fuel, a moderator is notneeded because the geometric configuration of the reactor 1021 willensure a satisfactory sustained reaction. The geometry of the chambercan be utilized to localize the reaction.

By utilizing the dependence of density of working fluid near theperiphery of the rotating device upon the speed of rotation, and thefact that the reaction depends on the density of the fluid, a system ofthis type could be made in which a reaction occurs only when the deviceis rotating above a selected angular velocity. This feature, togetherwith the extreme simplicity of rotary inertial thermodynamic systems,can give rise to a highly reliable device. The angular velocity effecton density and distribution of working fluid can be used to control theinternal reaction rate in a sealed system. In the case of a device whichis not sealed, control can also readily be effected by varying the gaspressure within the device. Of course, the structure which is used topromote the reaction within the working fluid does not all have to liewithin the rotating system itself; external nuclear reactor components,including moderators, fuel, control rods, shields, etc. can be used.

Rotary inertial thermodynamic compression devices which utilize achemical, nuclear or other reaction in the working fluid for heating arespecially suitable for the very high energy transfer rates desirable inan engine application. Materials are available for building compressorsof this general form with thermodynamic Carnot efficiencies in excess of50%.

RADIATION-ABSORPTIVE WORKING FLUID

In any of the embodiments, a radiation absorbtive working fluid can beused. The radiation field impinges upon the device in the region ofworking fluid to be heated. For example, in FIG. 5, a radiation fieldwould impinge on conduit segment 62 in the region shown occupied by heatexchange means 46, without means 46 present. Similarly, regions occupiedin FIG. 10 by means 133, 137 and 141 would be exposed to radiation. InFIG. 26, for operation as compressor, chamber 591 would be exposed toradiation, especially that part of it filled with liquid duringoperation.

In many applications, rotary inertial compressors are suitable as areplacement for other forms of compressor. These can be used in systemsrequiring distribution of compressed gas to operate other equipment,such as pneumatic hammers, turbines, and the like; or as part of a powerplant, where the primary application is the local conversion of theenergy represented by the compressed gas into mechanical work,electrical energy, or some other suitable form of energy.

Combustion of fuel within the gaseous working fluid of a gaseouscompressor can be used either as a high-impedance source of thermalenergy, by holding the flow of fuel constant, or as a low-impedancesource, by utilizing control of the rate of flow of fuel to control therate of delivery of heat and thus maintain the temperature of some pointin the system essentially constant.

In the case of a nuclear reaction releasing energy within a reactionzone in the working fluid, although the intrinsic heat source impedanceof a nuclear reaction is extremely high, the physics associated with theway in which the reaction occurs, and the way in which it feeds-back tosustain itself, can give rise to a low impedance for the heat source.For instance, in a reaction in which a moderator is used, an increase intemperature of the moderator can reduce the reaction rate. In a reactionutilizing just the gaseous component itself, an increase in reactionrate can lead to an increase in temperature, expansion of the gaseousworking fluid, decrease in the total mass present within the reactionzone, and decrease in the reaction rate. In these and other ways, thetemperature in the reaction zone can be held relatively constant. Thischaracteristic behavior is what one would ordinarily associate with alow thermodynamic impedance heat source. The flowing gases interact withmechanical and thermodynamic impedances, both within the device andexternal to it. This, again, illustrates the requirement that all of theimpedances in the entire system be taken into consideration in thestabilization of a rotary inertial thermodynamic device.

LIQUEFACTION OF COMBUSTIBLE GASES

In devices using internal chemical reactions for heating, it is notnecessary that the gaseous fuel be completely burned. Thus, the workingfluid could be gaseous fuel with only a small amount of oxidizer. Only asmall portion of the fuel is oxidized, and the remainder is used as theworking fluid in the thermodynamic process. FIG. 43 shows a compressiondevice for liquifaction of a combustible gas. The combustible gas (e.g.,a mixture of gases such as natural gas) is introduced at 1060, and asuitable oxidizer for reaction with the gas (e.g., air) is introduced at1061. The device 1062 is a rotary inertial thermodynamic gaseouscompressor to be operated on heat supplied by the reaction between thecombustible gas and the oxidizer. The device 1062 rotates on bearings(not shown), and rotary seals 1064 form gas-tight seals between theinlet and outlet conduits and the rotary conduit. Reaction stabilizationmeans 1063 is provided. The reaction (e.g., oxidation of a portion ofthe gas) occurs in region 1075. Alternatively the reaction stabilizationmeans can use a catalyst, especially when only a very small part of thegas is oxidized. Also, the oxidizer can be guided separately to thereaction region, and reacted in a suitable reaction chamber. This isdirectly analogous to the introduction of fuel into an oxidizer stream,as shown in FIG. 51, by means of conduits 1103 and 1104. This is helpfulin that compressor 1062 can be used with an adiabatic compressionresulting in a high working fluid temperature, without pre-ignition.Also, introducing the oxidizer into a suitable combustion chamber canfacilitate more complete combustion, and a more nearly stoichiometricreaction can be maintained. This can reduce unwanted by-productsotherwise often associated with combustion in the presence of an excessof fuel compared to oxidizer.

Gaseous working fluid leaves the rotating device in the directiondesignated by arrow 1070. A first portion of the gas, under the highpressure produced by the rotary device 1062, condenses in a chamber1076, giving up its heat of condensation to some external heat sinkthrough a thermodynamic impedance. This condensed working fluid leavesthe system through an exit port designated 1067, in the direction ofarrow 1072, through a suitable control means 9371. In this way, many ofthe reaction products can be removed from the combustible working fluidbefore it is further processed. An uncondensed portion continues in thedirection designated by arrow 1071 to a second chamber 1078, withinwhich it condenses, giving up its heat of condensation to some externalheat sink through another thermodynamic impedance. This condensedmaterial then leaves the system through outlet 1068, in the directiondesignated by arrow 1073, through an appropriate flow control means(valve) 1079. That portion which is uncondensed leaves in the directiondesignated by arrow 1074 through outlet 1069, fitted with appropriatecontrol means (e.g., a valve) 1080.

Consider, for example, the liquifaction of propane gas. This can beaccomplished by the introduction of a relatively small amount of airthrough inlet 1061. The reaction between the propane and the air wouldprovide the heat necessary to operate the compression cycle. Water fromthe reaction would condense in one chamber. The propane would condensein the other chamber. The gaseous reaction products from the combustionprocess would leave the system at outlet 1069. In this way, relativelylow contamination of the processed gas could be achieved, whileproviding a relatively economical way to accomplish the liquifactiondesired.

In FIG. 44 is diagrammed a system for the fractional liquifaction ofcombustible gases. Devices 1090 and 1095 are similar to device 1062 inFIG. 43. Following compressor 1090 are fractional condensation chambers1091 an 1093, similar to chambers 1076 and 1078 in FIG. 43. As manychambers as are needed may be used. These operate at successively lowertemperatures, separately condensing progressively lower boilingfractions of the combined stream of input gases and reaction products.After the lowest boiling fraction which can be condensed at thetemperatures and pressures available has been extracted, the remainingstream enters a second compressor 1095, and subsequent condensingchambers 1096 and 1098. In compressor 1095, a small additional amount ofoxidizer is reacted with the combustible working fluid. Compressor 1095multiplies the previous working fluid pressure by its compression ratio.At the higher pressure resulting, lower boiling fractions can condensein chambers 1096, 1098, etc.

Compression and fractional condensation means can be cascaded in thisway, to fractionate a large number of input gases, in a relativelythermodynamically efficient manner. From the fractional condensationmeans come streams 1092, 1094, 1097, 1099, etc. Some of these may bereaction products, separated from the condensing input gases, to be usedor discarded. A final uncondensed portion leaves as stream 1089, similarto that leaving through outlet 1069 in FIG. 43.

Systems of the foregoing type can utilize cascaded compression stages inwhich partial combustion occurs in each stage, with oxidizer and/or fuelbeing introduced in each successive stage. In a device of the type shownin FIG. 43, stable operation requires that the rotary inertialcompressor be capable of supporting the back pressure associated withthe condensation processes and with mechanical flow impedances invarious conduits of the system. As long as the amount of oxidizer issmall compared to the amount of combustible gaseous working fluid, therate of introduction of the oxidizer into the system determines the rateat which heat will be released by combustion, almost independently ofthe rate of flow of the combustible material itself, for a wide range offlow rates. By utilizing this effect, the gaseous compressor can be madeto have wide range of effective delivery impedances for deliveringworking fluid to subsequent portions of the system. Note that in gaseouscompressor 1062, the utilization of a single stage eliminates therequirement for having a means for heat rejection from the rotatingdevice additional to the heat rejection provided by the exit from therotating device of warmed working fluid. If desired, alternatively, eachcompressor could be a cascaded compressor of the general type diagrammedin FIG. 51, with oxidizer being distributed from inlet 1103, andcombustible gaseous working fluid entering at 1102 and leaving at 1115.

HEAT EXCHANGERS

The simplest heat exchange impedance and mechanical impedance controlmeans is a conduit. Such a conduit 891 is shown in FIG. 37. Fluid flowsthrough the conduit 891 in the direction 890. If the conduit 891 has alarge cross-sectional aperture 892 and short length 893, the conduit hasa low mechanical impedance to the flow of working fluid and a relativelyhigh thermodynamic impedance for the transfer of heat to or from thefluid. A conduit with a relatively small cross-section 892, or arelatively long length 893, presents a substantially higher mechanicalimpedance to the flow of working fluid, and a substantially lowerthermodynamic impedance to the flow of heat into and out of the workingfluid.

FIG. 38 shows an assembly 898 of parallel conduits 896 formed fromplates 894 separated by spacers 895. A device of this type can make moreeffective contact, and, therefor, more effective heat exchange with afluid passing through it. The assembly 893 is a simple extension of theform of conduit 891 of FIG. 37 and has essentially the same propertiesas an assembly of such conduits in parallel. In many instances such aconduit is a practical form of impedance control means. An example ofthis will be given in greater detail later.

In FIG. 39 is shown a heat exchanger and impedance control means 896consisting of a parallel assembly of slender metal tubes 897 which arein contact with each other in a larger metal tube 899. Heat istransferred to or from a fluid passing through the tubes 897 (in thedirection 904) to the walls of the tubes and thence through the wall ofthe outer tube 899 to its outside surface 903, through which heat isexchanged with some other portion of a system. Each conduit has arelatively very small inside diameter.

The device 896 is of a type which has been used as an intermediatestructure in the production of grids for klystron vacuum tubes. For itsuse in impedance control, it should be noted that there is arelationship between the optimum wall thickness of the tubes 897, andthe distance each tube 897 from outer tube 899. Those conduits locatednear outer tube 899 conduct a larger amount of heat because they conductheat to or from conduits located deeper within the impedance controldevice 897. For this reason, it is sometimes preferred that thethickness of the walls of the conduits be graded, increasing inthickness from within the device as the outer wall 899 is approached.

Devices of the type shown in FIG. 39 are particularly advantageous forproviding impedances in an intermediate range, with a lowerthermodynamic impedance than typically is obtainable with a simpleconstruction using a few conduits of the type shown in FIG. 37, but witha substantially higher mechanical flow impedance than is obtained withsuch conduits. In a device of the type shown in FIG. 39, an appreciableportion of the total thermodynamic impedance of the device can arisefrom the impedance to flow of heat caused by the finite conductivity ofthe material of which the walls of the conduit segments are made. Theheat exchanger 896 can have a cross-sectional shape other thancylindrical, if necessary. The device 896 produces intimate contact overa relatively large surface area between the metal of the tubes and thefluid flowing through the tubes. The metal has a relatively high thermalconductivity.

FIG. 40 shows another form of impedance control means, consisting of asintered metal porous plug or body 905, or other porous, high thermalconductivity material, such as beryllia. Working fluid flows through thepores of this material and exchanges heat with it and with its outsidesurface 906. In such an impedance control means, the bulk of thethermodynamic impedance for transfer of heat between a flowing workingfluid and the surface 906 arises from the thermal conductivity of theporous material, rather than from the exchange of heat between theworking fluid and the porous material. The working fluid is in intimatecontact with the porous material. For this reason, heat exchange betweenfluid and exchange means can be effectively accomplished with arelatively short length 907.

An alternative way to use an impedance control means of this type forexchanging heat with the working fluid is to utilize some form of energytransport means which results in heating of the porous material. Forexample, this type of impedance control means is particularlyadvantageous when heat is to be transferred by electromagneticinduction, in which the heat can be caused to develop within thematerial itself, without requiring that heat be exchanged with theexternal surface 906. In that case, there is no appreciable thermalimpedance arising from the thermal conductivity of the material of whichthe plug is made.

In FIG. 40 are also shown two optional electrodes 916 and 917 connectedto opposite faces 914 and 915 of the body 905. By utilizing anappropriate electrically conductive material as the porous material, thethermal energy can be released with the body 905 directly by passing anelectric current therethrough. This form of heating is particularlyadvantageous when the impedance control means has a short length 907 inthe direction 918 of flow of the working fluid. The advantage arisesfrom the elimination of any effect due to the thermal impedanceassociated with the finite conductivity of the porous material of whichthe device 905 is made. This allows the use of quite short impedancecontrol means while still retaining effective exchange of thermal energyto feed heat into the working fluid passing therethrough. Thus, thedevice 905 with its electrodes can be used as the means 910 forconverting electrical energy into heat energy in the rotary device shownin FIG. 36.

Several peculiarites in the operation of rotary inertial thermodynamicgaseous compressors are worth noting. First, gaseous working fluid nearthe axis is often at a much lower pressure and much lower density thanworking fluid near the periphery of the rotating device. The mass flowpassing any point in a single conduit is constant after the initialfluctuations of start-up decay to the steady state operating value. Forthis reason, the velocity of working fluid for the same cross-sectionalarea of duct increases with decreasing radius, corresponding to thedecrease in density of the working fluid as it approaches the axis. Forthis reason, impedance control means used near the axis should bedesigned for a relatively larger volume of flow than impedance controlmeans used far from the axis of rotation, although in both cases themass flow is the same.

Another effect of the smooth change in pressure with radius is that ifan acoustic wave occurs in the gas, and if that wave represents acertain fraction of the total pressure near the axis, it represents asteadily decreasing fraction of the total pressure of the gaseousworking fluid as the distance from the axis is increased. Conversely, anacoustic wave near the periphery in the working fluid represents aprogressively larger fraction of the total pressure of the working fluidat it approaches the axis. This can lead to a small acoustic wave nearthe periphery giving rise to a shock wave near the axis.

Acoustic waves can be produced within the conduits of a gaseous systemby many well known effects, such as vortex shedding, oscillation over anaperture, and oscillations resonant with some structure in the device.In addition to these gas dynamic effects, there are also effects whicharise from the interaction of these gas dynamic properties with thethermodynamic impedance within the system. For instance, theeffectiveness of a heat exchange means may be influenced by the onset ofvortex shedding within it. This can cause the temperature of the heatexchange means to change, which in turn affects the presence or absenceof the vortex shedding phenomenon within it, and its effectiveness inproducing heat exchange with the working fluid, which, in turn, affectsthe temperature, the density, and the effect of centrifugal forces uponthe working fluid. Variation in the effects of density and centrifugalforces, in turn, can give rise to variations in the effectivecompression or expansion in the working fluid produced by the rotaryinertial thermodynamic effects, thus giving rise to changes in the flowvelocity, which in turn feed back to affect the vortex phenomenon. Allof the foregoing phenomena have associated with them various timedelays, depending upon the nature of the materials, the geometry of thedevice, flow velocities, angular velocity of rotation, and othervariables of the system. For this reason, the detailed analysis of thebehavior of a pulse of pressure or temperature introduced within arotary inertial thermodynamic system can be quite intricate. However,many of the important stability properties of rotary inertialthermodynamic systems can be understood in terms of relatively sloweffects, which occur at a rate which is slow compared to the timerequired for the adjustment of internal temperatures and the propagationof internal pressure waves. These steady-state analyses lead to a fairlydetailed and consistent set of conditions under which rotary inertialthermodynamic systems can operate stably. The relations required forthese analyses are subject to experimental measurement. Typically, therelations involve the pressure drop as a working fluid passes through arotary inertial thermodynamic device, and the rate of flow of theworking fluid through it. This relationship, in turn, is affected bythermodynamic and mechanical impedances of the entire system, of whichthe device is a part. These relations give rise to criteria forstability for systems operating in an essentially steady statecondition, that is, operating with flow rates which are essentiallyindependent of time over periods of time comparable to the time requiredfor an acoustic impulse to propagate through the working fluid throughthe length of a typical conduit within the system.

Another effect is that, in the evolution of a gas from a liquid, withina rotary inertial thermodynamic system, the strong dependence of localpressure within the fluid upon distance from the axis of rotation givesrise to fairly well defined radii at which gas evolution begins tooccur, depending upon the temperature and nature of the working fluidsinvolved.

The availability of working fluids at various pressures within therotating devices makes it possible to utilize fluidic control andamplification systems formed within the rotating member itself. In thisway, the response of such systems to temperature and pressuredifferences and flow rates can be made almost arbitrarily intricate tosuit specific applications. However, control means of this typeultimately have the effect of controlling the effective impedancepresented by the rotating device, and/or by other parts of the system ofwhich it is a portion. The overall performance and stability of suchsystems can be understood in terms of the requirements on the impedancefor small fluctuations about a selected operating light. If thisimpedance is positive then operation at that point can be stable. If itis negative, then, in general, operation at that point will not bestable. That is, elaboration of the control means beyond those arisingsimply from the thermodynamic impedances and mechanical impedanceswithin the devices themselves, does not change the basic nature of thestability requirements.

NON-COMBUSTIBLE GAS LIQUEFACTION

FIG. 46 shows a rotary inertial thermodynamic cooling device 1029 whichis capable of cooling substances to extreme low temperatures, and isparticularly useful in liquefying air, hydrogen, etc. The device 1029has a single closed loop conduit of the type shown in my U.S. Pat. No.3,470,704. In this device section 1036 acts as a gaseous compressor of atype discussed previously. In region 1037 heat is rejected throughimpedance Z1032 to an external environment. Region 1038 is acountercurrent heat exchanger of the type illustrated in FIG. 9 of myabove-identified patent which conducts heat from conduit segment 1040 toconduit segment 1041 through impedance Z1033. Region 1039 represents acooling section in which working fluid progresses radially inwardlythrough conduit segment 1034. In doing so it expands, achieving a lowertemperature than that which it had in conduit segment 1040. Thislow-temperature working fluid then progresses through conduit segment1041 in the direction designated by arrow 1043. As it moves withinconduit segment 1041, it absorbs heat through thermodynamic impedanceZ1033 from working fluid in conduit segment 1040. In this way, aregenerative cooling effect is produced, so that the temperatureachieved near the axis of rotation in conduit segment 1034 can be quitelow. This can then absorb heat from some external source (e.g., a gas tobe liquified) through an impedance Z1035, producing cooling. Becauseworking fluid in conduit segment 1034 during normal operation is quitecold, it has a substantially higher density than would be achieved if itwere simply utilized in a device without the regenerative heat exchangemeans Z1033. This results in a substantially greater back-pressureassociated with the action of rotational inertial forces upon the masswithin conduit segment 1034. This allows the portions 1037, 1038 and1039 of the device to sustain a relatively large forward pressuredriving working fluid through it.

The flow of working fluid within this device 1029 depends uponimpedances for heat transfer, as well as internal mechanical impedances.Not only the internal impedance Z1033 by which the countercurrent heatexchange is accomplished, but also external impedances Z1035, Z1032 andZ1031 participate in determining the stability of operation. Inparticular, if Z1031 is large, then the heat source has a highcharacteristic impedance, and, therefore, the flow output impedance ofcompressor 1036 is relatively high, thereby satisfying the requirementsfor stable operation of a device of this type, as discussed in greaterdetail previously. Although for specificity 1036 is shown as being asingle-stage rotary inertial thermodynamic gaseous compressor, it is tobe understood that as many stages as needed can be used to provide therelatively high drive pressures required.

Suitable impedance control means within the various segments of conduitparticipate in forming the overall impedances, and participate inproviding for stable flow of working fluid.

One way to achieve the thermodymanic coupling represented by impedancemeans Z1033 is to utilize a gas freely moving between the tube sections1040 and 1041 and carrying heat by convection as indicated by the arrows1081. The gas chosen should have relatively low molecular weight so thatthe effects of compression upon it are not as great at the effects ofcompression on the working fluid which is producing the primary coolingeffect. For this reason, hydrogen and helium would be suitable gases foruse as the heat transfer gas. Other possible heat transfer means, inaddition to conduction and convection, include evaporative heattransfer.

FIG. 47 is a schematic diagram of a system for the liquefication ofgases, comprising a compressor 1044, a cooler 1046, and heat exchangemeans 1045. All of these can be combined in a single rotating device asshown in FIG. 48. The device shown in FIG. 48 includes a multiple-branchcascaded gaseous compressor 1048, bearing in a single cascadedcompression rotor at least two entirely separate branches. One branchserves as a compressor for the gas to be liquefied (taken in at an inlet1047), and another branch serves as a compressor to actuate aregenerative counter-current cooling device 1049 of the type shown inFIG. 46. The gas to be liquefied flows into the inlet 1047, iscompressed in the compressor 1048, and flows through a conduit 1050along the axis 1. The gas in conduit 1050 gives up its heat bycounter-current heat exchange to the very cold gas in conduit 1046 ofthe cooler, and exits through an expansion valve 1051 and an outlet1052. In this way an appreciable fraction of the gas is liquefied. Thisdevice illustrates the use of several disjoint branches of athermodynamic system which are physically part of the same device.Arrows 4732 and 4733 indicate which inlets of the compressor areconnected to which outlets.

One of the reasons for wanting to operate several branches of a rotaryinertial thermodynamic gaseous compressor in parallel is to allowsymmetrization of the device with respect to the axis of rotation. Asecond purpose is to allow cascaded compressor stages to be utilized ina symmetric fashion so that as working fluid pressure builds up towardsthe latter stages of the device, a rotational imbalance will not becaused by the additional mass of working fluid accumulated in the latterstages of the device. Many different branches can be interleaved witheach other.

STAGGER-WOUND HELICAL COMPRESSOR

FIG. 49 shows a single-branch cascaded gaseous compressor 820 whosestages are made symmetrical nearly about the axis of rotation by using alarger angular increment between successive stages than the number ofstages would require to fit in a single turn about the axis of rotation.In this way the stages loop about the axis of rotation many times. InFIG. 49, 1 is the axis of rotation, and 822 and 823 are connections fromthe rotary inertial thermodynamic cascaded gaseous compressor to otherdevices within the system. There are six compression stages 824. Thestages are interleaved so that in three stages the conduit has gonecompletely around the axis of rotation. 825 generally designates arotary structure supporting the stages. FIG. 49 is schematic, intendedsolely to represent the angular increments between the stages and theway in which they overlap. The angle between two successive stages isdesignated 826. The angular increment necessary to make the stages fitin a single pass around the axis of rotation is designated 827. Herethere is a twofold interleaving represented by angle 826 beingapproximately twice angle 827.

PARALLEL-CASCADED HEAT-PUMPS

FIG. 50 shows a rotary inertial thermodynamic device 1050 utilizing agaseous compressor 1053 comprising several separate branches, eachcontaining several stages of compression in cascade. These are utilizedto operate separate cooling devices 1057 and 1058. Device 1057 rejectsheat through impedance Z1054 to some external environment. Device 1058rejects heat through impedance Z1055 back to device 1057. Device 1058absorbs heat from some external source through an impedance Z1056,thereby producing a cooling effect. By utilizing a series of two or morecooling devices in this way, with thermodynamic impedances internal tothe rotating device coupling the cooling devices to each other, thewhole device 1060 will be capable of producing an extremely largetemperature differential. Various different working fluids can be usedin the separate cooling devices, with the working fluids beingappropriate to the various temperatures at which heat is absorbed andrejected by each of the cooling devices. Arrows 4734, 4735, and 4736indicate which inlets of the compressor are connected to which outlets.

The device 1060 has the capability of extracting heat from a load to becooled which has, in effect, a relatively high thermodynamic impedanceto heat flow; that is, from a load which makes it necessary to extractheat at a very low temperature. Also, heat can be extracted from lowimpedance sources which have a characteristic temperature which isintrinsically quite low, for example, in the liquefaction of gases.

In order to liquefy gases (e.g., air); an inlet 1047, tube 1050, and avalve 1051 carry the gas to be liquefied, in the same manner as in FIG.48. The gas in tube 1050 gives up its heat to the liquids in theevaporators of the coolers (as is indicated by the dashed arrows) tocool the gas to extremely low temperatures. Heating for the coolers 1057and 1058 can be by any of the means disclosed herein. For example, sucha device could be heated by combustion. A system utilizing a heat sourcebased on combustion and a liquefaction scheme of this type could beespecially useful for the liquefaction of combustible gases, such asnatural gas, and of air.

Although it is generally desirable that the temperature of operation ofa rotary inertial gaseous compressor using combustion within its workingfluid be high enough so as to insure that the combustion products remainin gaseous form, and not accumulate within the device, it is possible toprovide discharge means such as a trap 1083 (FIG. 43), for theelimination of such combustion products in the event that they do tendto accumulate. Utilization of such a mechanism is optional. For example,where powdered coal is used as the fuel, molten slag will be removedthrough the trap 1083. For some applications, it may be desirable tooperate device 1062 in a vacuum chamber (not shown) for greaterefficiency.

CASCADED COMPRESSOR WITH INTERNAL FUEL OXIDATION

FIG. 51 shows a cascaded gaseous compressor utilizing combustion withinthe successive stages to provide the heat necessary for their operation.Axis of rotation is designated 1. Through inlet 1101 is taken in aworking fluid 1102 which can support combustion. It is assumed forspecificity that this working fluid is an oxidizer, and that thereactant with it will be a fuel. This fuel enters at inlet 1103 todistribution system 1114. Fuel flows radially outwardly through conduitmeans 1104, a preheater 1106, and then through outlet 1112, to mix withoxidizer and enter the combustion area through stabilizing means 1105.Reactants from this combustion and unburned oxidizer progress radiallyinward through conduit segment 1118, then proceed radially outwardthrough heat exchange means 1108, which couples heat from the heatedworking fluid to some external heat sink, with a total effectivethermodynamic impedance Z1107. Fuel conduit segment 1109, preheater1110, orifice 1113 and combustion stabilizer 1111, operate in the sameway as their corresponding components in the first stage. Optionaldrains 1116 and 1117 are provided, if desired, for removing reactantswhich tend to accumulate in the system. Working fluid leaves the systemthrough outlet 1115 in the direction designated by arrow 1119.

Except for the means by which heat is introduced into the working fluid,the cascaded gaseous compressor in FIG. 51 is essentially similar inoperation to that in FIG. 10, with the exception that the introductionof heat into the working fluid is not necessarily isothermal, because ofthe nature of combustion. The impedance Z1120 and associated heatexchanger 1121 can be provided in conduit segment 1122 in the event thatthe inlet working fluid is already at a temperature roughly near that atwhich heat is to be rejected. (In FIG. 10 it is assumed that the workingfluid enters the system at a relatively low temperature.) There areseveral reasons for utilizing partial combustion in each stage ofcompression. In a practical system, the maximum temperature which can beachieved in the rotating device is limited by the properties ofmaterials and by the angular velocities available. For this reason, itmay not be feasible to operate a full combustion Carnot cycle in asingle stage. However, several cascaded stages of compression can each,separately, approximate fairly closely a Carnot cycle by utilizing heatrejection through impedances Z1120 and Z1107, such that the combustion,when it occurs, leads to a rise in temperature of a magnitude which,after adiabatic expansion in conduit segments radially inward from thecombustion zone, has reduced the temperature of working gases, andallows essentially isothermal heat rejection to occur. It is withinpresent materials technology to achieve, in this way, a Carnot cycleefficiency in excess of 50 percent. The maximum temperatures occurringin a Carnot cycle with an efficiency of 50 percent and heat rejectiontemperature of 400° Kelvin are substantially lower than the maximumtemperatures which would be produced by total reaction of, for example,air with a typical hydrocarbon fuel, such as gasoline or propane. Thisuse of successive stages with combustion allows the maximum temperatureto be held to a low enough value to be feasible with currently availablematerials, and also helps to insure complete combustion of the smalleramount of fuel used in each stage, thereby reducing the production ofundesirable byproducts.

Means for providing rotation, bearings for support, and rotary seals forfeeding in working fluid and fuel, and for receiving working fluid fromthe outlet of the device, have, for simplicity, not been shown. Agaseous compressor utilizing combustion or other reaction within itsworking fluid can be used, not only to provide its own operating heat,but also to provide operating heat for other rotating devices throughappropriate thermodynamic impedances. In FIG. 51, as well as othersystems disclosed herein utilizing combustion for heating, appropriatemeans for initiating such combustion are included if necessary in thecombustion area (inwardly from the combustion stabilizer). However, inmost of the drawings herein, these ignition mechanisms have not beenshown for the sake of simplicity. In some cases, heat of compression canprovide ignition, as in a diesel engine.

ABSORPTIVE ROTARY THERMODYNAMIC COMPRESSOR

FIG. 52 is a diagram of an absorption cycle rotary inertialthermodynamic compressor in which an absorbent fluid componentcirculates entirely within the rotary inertial thermodynamic device, anda gaseous component is absorbed from outside the device and delivered tooutside the device, either to other components of a system which rotatewith it, or are stationary. Working fluids for use in this embodimentinclude the following well known pairs: (a) water and ammonia, withammonia vapor as the gas; (b) a water solution of lithium bromide, withwater vapor as the gas; and (c) a water solution of lithium iodide, withwater vapor as the gas. Of course, other known pairs also can be used.

Gaseous working fluid flows into the system at inlet 672 in a directiondesignated by arrow 670. It enters chamber 673, where it contactsabsorbing fluid 674 at surface 687, and is absorbed thereby. Thiscombination of absorbing fluid and the absorbed gaseous component whichhad entered the system moves radially outward through conduit section676 in the direction designated by arrow 675, passing through a rotaryinertial trap 691, into a chamber 679. Chamber 679 is supplied with heatfrom a heat source 678 through impedance Z677. Impedance Z677 representsthe total impedance for heat flow into working fluid within chamber 679,including that part of the impedance which is external, and that partwhich is internal, to the chamber. Gaseous form working fluid is evolvedfrom working fluid solution 680 in chamber 679, and proceeds as a set ofalternating slugs of liquid and gas, radially inward in a directiondesignated by arrow 682 through a lift tube 683, exiting from the lifttube 683 at outlet 684 in chamber 685. In chamber 685, the liquid andgaseous components exiting at exit 684 are separated, with liquidcomponents leaving chamber 685 and flowing radially outward and intoconduit segment 689. Gaseous working fluid leaves chamber 685 throughthe outlet of the rotary inertial thermodynamic compression device 690,in the direction designated by arrow 671. Gaseous form working fluid inchamber 685 is at a higher pressure than in chamber 673. For thisreason, liquid working fluid, exiting chamber 685, flows radiallyoutward to a surface 686 in conduit segment 689 which is radiallyfurther outward than surface 687 in chamber 673. This difference inradial position is designated by numeral 688.

Conduit segment 689 forms a rotary intertial trap, within which liquidworking fluid flows in the direction designated by arrow 692. Liquidworking fluid exits from conduit segment 689 into chamber 673, and flowstherein, absorbing gaseous working fluid and leaving therefrom throughconduit 676, continuing the cycle. In this way, liquid working fluid,acting as an absorber, flows in a closed cycle within the rotaryinertial thermodynamic device shown in FIG. 52, and gaseous workingfluid flows through it in a single pass, entering at 672 and leaving at690. Conduit segment 676, trap 691, chamber 679 and lift tube 683together comprise a "lift tube" type of compressor which is disclosed inmy co-pending U.S. patent application Ser. No. 843,167, filed July 18,1968, now U.S. Pat. No. 3,559,419, issued Feb. 2, 1971. This subsystemhas a maximum pressure into which it can deliver liquid and gaseousworking fluid at the exit of lift tube 684 in diagram 52. Also, there isa maximum pressure which can be supported across rotary inertial trapmeans 689, considered together with liquid form working fluid level 687in chamber 673. Whichever of these pressure differences is smallerdetermines the maximum pressure at which gaseous form working fluid canbe delivered at exit 690.

Depending on the nature of the combinations of working fluids usedwithin this sytem, chamber 673 may or may not be required to dissipateheat. In the event that it is required to dissipate heat it is coupledto the external environment through a thermodynamic impedance designatedZ693. Z693 is used here to designate both internal and externalthermodynamic impedances associated with the flow of heat working fluidsin chamber 673.

FIG. 53 shows two types of relationship between pressure and flow, for adevice of the general form in FIG. 52, depending on whether thelimitations on maximum pressure arise from the failure of the trap 689to support pressure, or failure of the lift tube assembly to deliverworking fluid at pressure. Both have in common line segment 695,representing compression under normal operation, with the delivery ofgaseous form working fluid in the direction designated by arrow 671 atoutlet 690. In the event that the limitation upon the maximum pressuredifference which can be delivered between outlet 690 and inlet 672 isdetermined by failure of trap 689, the forward pressure near zero flowis nearly constant, with output pressure depicted by line segment 4740,and reverse flow is represented by line segment 696. In the event thattrap 689 can support a back pressure larger than that into which thelift tube subsystem can deliver liquid and gaseous working fluid,forward compression at nearly zero flow has a form indicated by linesegment 4741, and there is a gap, designated 698 in FIG. 52, afterforward flow has ceased and before reverse flow begins. In that case,reverse flow follows the line segment 697. The maximum back pressureoccurring at the onset of reverse flow designated 699, will depend onwhich of the two portions of the device fails in the reverse mode atlower pressure. It could be by back-flow through trap 689, or it couldbe by back flow through trap 691. In the Figure as drawn, the back flowwould occur through trap 689. The two different ways in which themaximum pressure can arise give rise to pressure flow relationshipswhich have in common a stable operating forward compression segment 695.However, branch 696 begins at the intercept of branch 4740 with the zeroflow axis. For this reason, if several parallel branches were utilizedwith a system having that type of limitation, small variations ingeometry or thermodynamic impedance within each of the branches couldgive rise to slightly different pressures such that, as the totalparalleled flow approached zero, one of the branches could be forcedinto reverse flow. In the case where the relationship between backpressure which can be supported by trap 689 and the maximum forwardworking pressure delivered by the lift tube subassembly is such thatthere is a gap 698, this gap makes a set of parallel branches act in anunconditionally stable manner, i.e., if the system is operated into aclosed vessel so that it delivers gaseous working fluid at the maximumpressure which it can produce, there is no tendency for the flow ofworking fluid to reverse in any one of the branches.

It should be noted with regard to the operation of any of the rotaryinertial traps, e.g. 689 or 691, that if the tube, in this case conduitsegment 689 or conduit segment 676, has too small a diameter, it ispossible for a gaseous form of working fluid to drive ahead of it liquidform working fluid, and empty the trap. That would give rise to areverse flow characteristic more nearly like that designated by linesegment 700 in FIG. 49. The requirement for normal trap operation isthat the gaseous form working fluid be able to form bubbles which moverelative to the liquid form working fluids, so that the liquid continuesto remain in the trap, that is, the minimum tube diameter is appreciablygreater than the expected bubble diameter. Because of the centrifugalforces acting on the liquid form working fluid this requirement isrelatively easily satisfied.

In an absorptive cycle system it is often desirable to provide forheating a fluid to drive off absorbed working fluid, in addition to thatheating which is utilized in evolving gases to operate a lift tube.Provision is made for this in FIG. 52 by the option of adding a smalldam 850 extending radially inward from outer surface 853 of chamber 685.This dam, if used, provides space for the accumulation, againstoutermost wall 853, of absorbent fluid 852, in which location it canreadily be heated through impedance source Z851 by a heat source 854.This heat source may be the same as source 678. Use of such anadditional space for additional heating is optional. With some workingfluids under some operating circumstances it is desirable, with othersfor specific applications it is not necessary. Heat exchanges amongvarious flows within the device have not been shown, for simplicity.

CASCADED ABSORPTIVE AND GASEOUS COMPRESSORS

It is feasible to connect several different forms of rotary inertialthermodynamic compressor in cascade. For instance, an absorption typecompressor of the form shown in FIG. 52 could be used to deliver gaseousworking fluid into a cascaded gaseous rotary inertial thermodynamiccompressor. The heat flow through the two compression units could alsobe in series, with heat being delivered initially to the cascadedgaseous compressor and its waste heat being utilized as the actuatingheat designated heat source 678 in FIG. 52, for the absorptive typecompressor. Such a combination is particularly advantageous wheregaseous form working fluid must be taken in at a relatively lowpressure. The absorptive type compressor would serve to produce aninitial compression, after which the gaseous compressor is fed at arelatively high intake pressure. The gaseous rotary inertialthermodynamic compressor operates to multiply the input pressure by afactor, depending upon its impedance and operating points. By utilizinga precompressor, it is possible to shift the operating points of thecascaded gaseous compressor so as to obtain the overall compressiondesired with a smaller number of stages. Such a combination offers ahigher overall thermodynamic efficiency, where a very large ratio ofoutlet to intake pressure is required, than might be readily achieved bya gaseous unit alone. Utilization of such a cascaded system allows anextremely low mechanical intake impedance to be realized in athermodynamically efficient manner. Furthermore, where parallel branchesare desired, the utilization of such a cascade allows one of the devicesto provide the stabilizing pressure flow relationship for the otherdevice, so as to make the entire branch unconditionally stable. Thus, itis possible to construct multiple branch systems, utilizing severaldifferent forms of compressor in each branch, and, if desired, utilizingdifferent forms of compressor in different branches, such as cascadedgaseous compressor in one branch, an absorption type compressor inanother branch, a liquid-gas compression cycle in a third branch, etc.,or combinations of these or others in any single branch. As long as theimpedance requirements and the pressure flow relationships aresatisfied, the operation of such a system will be stable. By choosingproper combinations, or by utilizing additional constraints, such as asimple valve assembly, it is possible to make the operation of suchsystems unconditionally stable over very wide operating ranges.

One of the advantages of the absorptive type system in which theabsorbent follows a closed cycle and the gaseous component is part of anopen cycle, is that it is possible to achieve a very large volume ofintake with a high compression ratio in a compact device. For example,if water vapor is the gaseous component and a salt solution of lithiumbromide with water or lithium iodide with water is the absorbent, adevice with a diameter of only a few inches spinning at 1000 rpm to 3000rpm is capable of handling a substantial volume of intake and providinga pressure differential in excess of 300 mm mercury. Potentialapplications for such a device include freeze-drying of foods, as wellas refrigeration and air conditioning. Systems of this type can bescaled down to a quite small diameter or up to relatively largediameters depending on the nature of the working fluids, pressuredifferentials, and pumping capacities required.

COUNTER-CURRENT HEAT EXCHANGE: ABSORPTIVE HEAT PUMP

In absorption cycle cooling units, the maximum thermodynamic efficiencyavailable is determined partly by the maximum temperature at which heatcan be accepted from the actuating heat source. In such devices, thechemistry of the absorption process imposes temperature and efficiencylimitations on single stage configurations. For absorbent and gaseousworking fluid combinations in which the absorption of the gaseous formof working fluid results in the evolution of heat, this limitation canbe substantially ameliorated through the use of a counter-current heatexchange system in which part of the heat evolved during absorption ofgaseous working fluid is utilized in providing the heat necessary forthe evolution of gaseous working fluid in a different part of thesystem. In FIG. 56 is shown a system 1400 utilizing this principle.

In the system 1400, the absorption of vapor form working fluid by arelatively concentrated absorber is allowed to occur at a hightemperature, so that the heat evolved therefrom can be utilized to heatan absorbent at a somewhat lower temperature and lower concentration toevolve gaseous working fluid therefrom. In FIG. 56, two extendedchambers, 1435 and 1438, are utilized in conjunction with extended heattransfer impedance means Z1405 to form a counter-current heat exchanger.Thermodynamic impedance Z1405 convey heat from liquid working fluidabsorber, or `liquor`, 1414, progressing in the direction of arrow 1416within chamber 1435, to liquor 1415 progressing in the direction ofarrow 1417 in chamber 1438. In so doing, they allow the liquor toexchange heat in the necessary counter-current fashion. Gaseous workingfluid is evolved within chamber 1438 from liquor 1415. This gaseousworking fluid 1439 travels in the direction of arrow 1573, giving upheat to liquor 1415 through distributed impedance Z1575 incountercurrent fashion, leaving chamber 1438 at outlet 1576, proceedingthrough conduit 1426 in the direction of arrow 1433 into counter-currentheat exchanger 1571, characterized by distributed thermodynamicimpedance Z1570, in which it exchanges heat with cold vapor from chamber1431 and may partially condense, thence into condensing chamber 1427,wherein condensation is completed, giving up its heat of condensation toan external heat sink through an overall thermodynamic impedance Z1409,representing internal and external heat-exchange impedances. Thiscondensate leaves condenser 1427 through outlet 1428 into conduit 1429,containing, if desired, an appropriate flow control means Z1410. Thisflow control means has a mechanical impedance and can, for example, beof the form of one of the self-adjusting impedances discussed earlier.

From conduit 1429 condensate 1430 progresses into chamber 1431, whereinit evaporates at reduced pressure, absorbing heat from an external heatsource through an overall thermodynamic impedance Z1411. This is theprocess by which heat is moved from the source supplying heat throughZ1411 to the sink absorbing heat rejected through Z1409. Low pressurevapor-form working fluid progresses through conduit 1432 in direction ofarrow 1434 into chamber 1435. This vapor form working fluid 1436 is thenabsorbed by liquor 1414. As the liquor progresses from inlet 1425through chamber 1435 to outlet 1419, it becomes progressively moredilute. At the same time, its temperature decreases. The relationshipbetween temperature, concentration of absorbent, and vapor pressure isutilized in this way in that the temperature is reduced so that theabsorption of vapor-form working fluid 1436 by absorber 1414 proceedswith only small deviations from thermodynamic equilibrium as theabsorber progresses through chamber 1435. In the regions between dottedlines 1404 and 1406, the concentration of the absorber is high enough sothat the absorption of low pressure vapor occurs at a temperature higherthan will be required for evolving higher pressure vapor in chamber 1438from a more dilute solution of the absorber.

Because the evolution of gaseous working fluid 1439 in chamber 1438 mustoccur at a higher pressure than that present in chamber 1435, in orderto provide the pressure necessary for condensation in chamber 1427 andrejection of heat through impedance Z1409, the relationship betweentemperature, concentration of absorber, and vapor pressure requires thatthe temperature of the solution be higher in order to evolve vapor fromworking fluid, for any given absorber concentration, in chamber 1438than in chamber 1436. The higher temperature required to evolve vapor inchamber 1438 for a given liquor concentration means that there exists amaximum degree of dilution of absorber 1414 in chamber 1435 above whichfurther dilution by absorption of gaseous working fluid cannot occur inan equilibrium fashion at a temperature high enough to actuate theevolution of vapor from any of the working fluid present in chamber1438. From this point, designated by dotted line 1406, to the end ofchamber 1435, all additional absorption of vapor form working fluidoccurs with the rejection of heat of absorption through an impedanceZ1407 to some suitable heat sink. The further diluted absorber 1414 thenleaves chamber 1435 at outlet 1419, through conduit 1420 containing flowcontrol impedance 1412, and into chamber 1438 at inlet 1421. The diluteabsorbent entering chamber 1438 at inlet 1421 progresses in thedirection of arrow 1417. This liquor 1415 gradually evolves vapor 1439as it absorbs heat transferred into it through thermodynamic impedancesZ1405 and Z1575. The heat transferred through Z1405 is released inchamber 1435 by the absorption of a lower pressure vapor by a moreconcentrated absorbent. It is this portion of the process, occurring inchamber 1438 between inlet 1421 and dotted line 1404, that accounts forthe increased efficiency of a system of this type.

As liquor 1415 progresses in direction 1417 through chamber 1438, itsconcentration is gradually increased as it evolves vapor. As thisoccurs, its temperature also is gradually increased to allow thecontinued evolution of vapor in a nearly equilibrium manner. However, asthe concentration of the absorber increases, it reaches a concentrationabove which no temperature appearing in chamber 1435 is sufficientlygreat to allow evolution of vapor 1439 at the higher pressure appearingin chamber 1438. In the region in chamber 1438 between dotted line 1404and outlet 1422, the absorber is more concentrated than this value. Inthis region, further evolution of vapor is actuated by heat transferredfrom heat source 1403 through thermodynamic impedance Z1402 intoabsorber (liquor) 1415.

This thermodynamic process of counter-current absorption andre-evolution of vapor form working fluid allows the process to betailored to a wide range of temperature differences between condensor1427 and evaporator 1431. As the temperature difference betweenevaporator and condensor is made smaller, the vapor pressure differenceis also made smaller, so that the vapor pressures in chambers 1435 and1438 become more nearly equal. This allows a progressively largerfraction of the total heat exchange process, occurring with absorptionof vapor in chamber 1435 and evolution of vapor in chamber 1438, to beaccomplished through the exchange of heat between the two chambers,utilizing impedance Z1405. At the same time, a smaller amount of heatinput through impedance Z1402 and heat rejection through impedance Z1407accompanies the total flow of heat between the two chambers. In thisway, the overall heat pumping ratio, that is, the heat transferred(taken in through impedance Z1411 and rejected through impedance Z1409),divided by the heat taken in through impedance Z1402 from heat source1403, becomes larger, the smaller the temperature difference between theevaporator and condensor.

After it has reached the maximum concentration desired in thethermodynamic process, absorber 1415 leaves chamber 1438 through outlet1422, proceeds, through conduit 1423 through pump means P1413, thence indirection of arrow 1440 through conduit 1424, to reenter chamber 1435 atinlet 1425. Impedance Z1441 of impedance Z1405 represents thermalcoupling between fluid flowing in conduit 1424 and liquid 1415 inchamber 1438. This allows for the precooling of high temperatureabsorbent before it enters chamber 1435. FIG. 56 is intended as aschematic system diagram to facilitate the explanation of thethermodynamic processes occuring therin.

It is to be understood that pump means P1413 and flow control meansZ1412, can be located at suitable places within the system. For example,the region of chamber 1438 between dotted line 1404 and outlet 1422, andpump means P1413, can be replaced partially or in their entirety by alift tube assembly, utilized to provide both the additional heating andthe desired pumping. Alternatively, chamber 1438 could be divided atlocation 1404 to allow a lift tube mechanism to be placed between thetwo portions resulting of chamber 1438. This would be a particularlyadvantageous location for a lift tube, because the absorbent 1415 hasnot yet been concentrated so greatly as to make the amount of vapor formworking fluid, yet to be evolved, so small as to render relativelyineffective the operation of a lift tube transport system.

The closed cycle process depicted in FIG. 56 can be opened at locations1443 and 1442 to provide an open cycle system with respect to the flowof the absorbed vapor, and a closed cycle system with respect to theflow of the absorbent, in much the same way as was done with the devicein FIG. 52.

It is to be understood that use of a buffer gas, where appropriate, iscompatible with the counter-current heat exchange process set forth inFIG. 56. With some combinations use of a buffer gas is well known, e.g.use of hydrogen as a buffer with water as the absorber and ammonia asthe vapor.

FIG. 57 shows the structure of a rotary inertial thermodynamicembodiment utilizing the system shown in FIG. 56. For the sake ofsimplicity, the various conduits in FIg. 57 have been shown as if theylay essentially in a single plane parallel to the axis of the rotatingdevice. Actually, however, this is not usually true.

Each of the chambers 1458, 1461, 1470, 1469, 1478, 1475 and 1473 extendsentirely around the axis of rotation 1 as a figure of revolution, havingan cross-section the crosssection shown in FIG. 57. In each chamberexcept chamber 1473, a dam stretches across each chamber parallel to theaxis and extending radially inwardly from the outermost surface of thechamber in to a point closer to the axis 1 than the surface of theliquid contained within that chamber during operation. These dams arenot shown in FIG. 57. However, when liquid is fed into one of thechambers, for example, chamber 1469 at inlet 1486, it is to beunderstood that the entry to the chamber is near the dam on one facethereof, and that the exit 1485 is near the dam on the other face. Inthis way, liquid working fluid is forced to flow around thecircumference of the chamber so as to spend the maximum distance withinthe chamber. FIG. 58 is a cross-sectional schematic view showing thestructure of such a dam.

In FIG. 58, 1 is the axis of rotation. The direction of rotation isdesignated by arrow 1505. The inlet is at 1501, and the outlet is at1502. Dam 1503 extends radially inward from outer surface 1506.Centrifugal force hold the liquid against the surface 1506. The surfaceof the liquid is 1504. The innermost surface of the chamber is 1507.With this configuration, liquid entering the chamber at 1501 is forcedto traverse the chamber in the direction designated by arrow 1508.

In chamber 1475, the direction of peripheral flow of the liquid workingfluid is not critical. In chamber 1461 this is also the case. Inchambers 1470 and 1469 the relative directions of flow of liquid workingfluid are important in establishing effective operation as acountercurrent heat exchanger. For this reason, we choose a directionconvention. Direction A at an inlet means that working fluid entering achamber through that inlet flows away from the viewer looking directlyat the diagram. This means that it will have gone into the diagram,around and come back to contact the diagram and depart through theoutlet. The letter T means that the liquid moves towards the viewer, inthe opposite sense to that designated by the letter A. Flow of variousworking fluids is designated by arrows in FIG. 57. Heat exchanger means1571 of FIG. 56 has been omitted.

In connection with the system diagrammed in FIG. 56, it was mentionedthat instead of utilizing a pump P1413, it is also feasible to breakchamber 1438 at location 1404, and introduce into the flow pattern atthat location a lift tube compression assembly. This has been done inFIG. 57. Chamber 1478 is the chamber in which gaseous working fluid isdriven off from the absorbent by heat from heat source 1450, enteringthe device through thermodynamic impedance Z1451. The combination ofliquid and gas moves radially inward through lift tube 1466, enteringchamber 1475 at inlet 1484. The liquid component of this working fluidproceeds peripherally around chamber 1475 in accordance with thetechnique shown in FIG. 58. This liquid working fluid 1476 receives heatfrom heat source 1452 through thermodynamic impedance Z1453 driving offvapor 1477. Heat sources 1450 and 1452 can be the same. Vapor-formworking fluid 1477 progresses radially inward through duct 1510, intocondensing chamber 1473. Within chamber 1473 it condenses, giving up itsheat of condensation through thermodynamic impedance Z1454 to someappropriate heat sink. Condensate accumulates against outermost surface1474 of chamber 1473, and drains therefrom into conduit 1467. Thesurface of the condensate in conduit 1467 is indicated at 1511. Thiscondensate proceeds in the direction shown by the arrows, throughself-adjusting impedance control means 1481, and continues therefrom tochamber 1458, in which it evaporates at reduced pressure. Concentratedabsorber leaves chamber 1475 through outlet 1483, proceeding throughconduit 1464 to enter chamber 1470. Note the letter A at inlet 1487 tochamber 1470. This denotes that the concentrated absorber, upon enteringthat chamber, proceeds away from the viewer looking at FIG. 57. Onentering chamber 1470, hot concentrated absorber gives up heat throughheat exchange means 1471, generally identified by distributedthermodynamic impedance Z1455, which transfers heat from liquid inchamber 1470 to liquid in chamber 1469. As the absorber progressesthrough chamber 1470, it is exposed to vapor from evaporating liquid inevaporator 1458. It absorbs this vapor, becoming progressively moredilute as it does so, and giving up the heat released in the absorptionprocess through impedance Z1455 to heat the liquid absorber in chamber1469, and drive therefrom vapor form working fluid through conduit 1468into condensor 1473.

After it has reached the degree of dilution discussed in connection withlocation 1406 in chamber 1435 of FIG. 56, the working fluid in chamber1470 proceeds radially outward through outlet 1488 to enter chamber 1461at inlet 1489. It then proceeds peripherally around chamber 1461,absorbing vapor form working fluid from evaporating liquid in evaporator1458, and giving off the heat released in the absorption process throughimpedance Z1456 to some suitable heat sink. The heat of vaporization ofliquid working fluid in evaporator 1458 is supplied from some externalsource through a total thermodynamic impedance Z1457. It is at thislocation that useful cooling work is done.

The dilute absorbent from chamber 1461 proceeds through outlet 1490 toconduit 1463, and thence into chamber 1469 at inlet 1486. Note theletter T at inlet 1486, denoting that liquid working fluid flows towardsthe viewer looking at diagram 91. This is in the opposite sense ofmotion to that occurring for liquid in chamber 1470. In this way,distributed thermodynamic impedance Z1455 acts to provide thecounter-current heat exchange required for operation of the system inaccordance with the principles set forth in connection with the diagram56. After completing its peripheral travel within chamber 1469, therelatively concentrated absorber leaves chamber 1469 through outlet1485, proceeding through conduit 1465 to re-enter the gas evolutionchamber lift tube assembly at inlet 1479. It then proceeds peripherallyaround the device within chamber 1478 to complete the cycle.

Absorber in chamber 1469 becomes progressively more concentrated as itflows peripherally within the chamber. During this process ofconcentration, the temperature at which it is in equilibrium with vaporat the pressure in condensor 1473 increases, and its temperaturecorrespondingly increases. In this way, both the absorption process inchamber 1470 and the evolution process in chamber 1469 occur in a nearlyreversible fashion.

Liquid in chamber 1469 and chamber 1477 is pressed upon by vapor inequilibrium with the vapor in condensor 1473. This is at a relativelyhigh pressure, associated with the rejection of heat through theimpedance Z1454 during condensation of the vapor. In evaporator 1458,vapor is at relatively low pressure. For this reason, the liquid level1514, in chamber 1470, is radially closer inward to axis 1 than theliquid level 1513 in chamber 1469. The difference between the radialpositions of the two liquid surfaces is designated 1512. In a similarfashion, the liquid surface 1516 of condensate evaporating in chamber1458 is closer to axis 1 than the liquid level 1511 in conduit 1467. Theliquid surface in chamber 1461 is at essentially the same radialdistance from axis 1 as that in chamber 1470. Similarly, the liquidlevels in chambers 1469 and 1475 are at essentially the same distancefrom axis of rotation 1.

Conduit 1463 and conduit 1464 are also formed into rotary inertialimpedance control means to support a pressure difference associated withthe difference in the levels of liquids in chambers 1461, 1469, 1470 and1475. Taken together with the chambers which they interconnect, theseconduits form a liquid trap type of impedance control means, which hasbeen discussed above in connection with FIG. 26.

There is a significant difference between the problems of coupling heatinto a chamber such as 1475 in order to cause the evolution of gaseousworking fluid from liquid 1476, and those associated with coupling heatout of liquid 1514 in chamber 1461 released by the absorption of vapor.Similarly, the problem of transferring the heat of absorption fromchamber 1470 into chamber 1469 can be solved by the use of a combinationof the solutions to problems used with chambers 1461 and 1475. Inchamber 1475, heat from heat source 1452 is coupled to outermost surface1515 so as to heat the portion of liquid 1476 which is radially furthestfrom the axis of rotation 1. Thermal convection then causes this heatedliquid to progress radially inwardly. In this way, the bulk of theliquid is easily heated by heat coupled to one surface to which it isexposed. Evolution of vapor from the absorbent 1476 typically results inan increase in its density. Thus, the material which has given up heatin the course of the evolution process also is denser, and returnseasily to receive additional heat through surface 1515.

The foregoing processes, together, participate in forming thermodynamicimpedance Z1453. However, in chamber 1461, the absorption of vaporproduces heating in absorbent 1514 at a region near its radiallyinnermost surface 1516. This has two effects: the heated materialordinarily is less dense because of thermal expansion. Simultaneously,the dilution process typically serves to decrease the density of theabsorbent. These two effects combine to cause the working fluid whichhas absorbed vapor to tend to remain near the radially innermost surface1516. For this reason, it is desirable to provide heat transfer meanswithin chamber 1461 by means of which the thermodynamic impedance withinthe chamber can be reduced. These are represented schematically by heattransfer devices 1462. In a small rotary inertial device these can bethermal conductors such as thermally conductive posts extending radiallyoutwardly to meet surface 1509 and transfer heat thereto. These,together with the transfer properties within the liquid itself,participate in forming the total thermodynamic impedance Z1456, throughwhich heat of absorption released within chamber 1461 is rejected to anenvironment.

Distributed thermodynamic impedance Z1455 is implemented by heatexchange device 1471, including heat exchange posts 1482. Removal ofheat of absorption in chamber 1470 has essentially the same problemsassociated with it as does removal of heat of absorption in chamber1461. For this reason, heat transfer means 1482 are included withinchamber 1470. For specificity, these are depicted as being thermallyconductive material. In FIG. 57, thermally conductive and insulatingmaterials are appropriately cross-hatched.

The transfer of heat of absorption from chamber 1470 is implemented bythe thermally conductive rods 1482. When this heat is delivered tosurface 1518 of heat exchange device 1471, it is then available forconvective heating of liquid in chamber 1469. This convective heatingresembles that in chamber 1475, and for this reason does not requirespecial implementation by means of conductive devices within the liquiditself.

In chamber 1458, provision is made for bleed of fluid through a smallport 1491. This port is located on the opposite side of a radial damnear inlet 1517. During start-up, absorber may be located in chamber1458. The flow pattern established by the dam, inlet 1517 on one sidethereof, and outlet 1491 on the other side thereof allows condensatefrom condenser 1473 entering at outlet 1517 to flush ahead of it theabsorbing fluid chamber 1458 through outlet 1491. This clears thechamber. The absorbent moves radially outwardly into chamber 1461, whereit mixes with other absorbent fluid, and enters the correct absorbentfluid flow cycle.

The closed cycle device shown in FIG. 57, can be converted to a devicewith a closed cycle for flow of absorbent fluid and an open cycle forflow of absorbed gaseous working fluid, by breaking the system open atlocations 1519 and 1520. This removes from the system chambers 1458 and1473, and connecting conduit means 1467 therebetween.

Condensing and evaporation chambers 1473 and 1458 are depicteddiagramatically. Their configuration can be modified to be appropriatefor the heat capacity required and to implement heat exchange, bothinternally and externally, in order to obtain desired values forthermodynamic impedances Z1454 and Z1457.

A device of the type shown in FIG. 57 can be built fairly simply bydividing the structure axially into laminations, so that conduits eitherare formed as holes through the laminations, or as slots cut into theirsurfaces. In the same way, chambers can also be formed. These laminaeare then assembled and bonded to form the complete unit. The techniqueis analagous to the techniques of assembly of conduit and impedancecontrol means from laminations with slots, as is discussed herein below.

When no buffer gas is used in device 5000, the radial difference 1512and the difference between radii to surfaces 1516 and 1511 support thepressure difference between evaporator 1458 and condensor 1473. This isappropriate with some absorption cycles, such as water and lithiumbromide with water vapor, or water and lithium iodide with water vapor.For ammonia and water systems a buffer gas is often convenient, withcondensation and evaporation determined by partial pressures of ammoniarather than total pressures. A suitable "rectifier", not shown, as iswell known for ammonia and water systems, can be used. However, thecountercurrent absorbtion and reevolution process shown in FIGS. 56 and57 is particularly well suited to absorbtion cycles with a relativelynon volatile absorbent, such as a dissolved salt.

IMPEDANCE RELATIONSHIPS IN CASCADED SYSTEMS

Various forms of devices with different flow impedances can be cascadedin series. For instance, if two rotary inertial thermodynamic gaseouscompressors with substantially different thermodynamic impedances arecascaded, the result is a device which has the capability of deliveringa high forward pressure at low flow and at high flow a relatively lowerpressure, without having the rapid dropoff in compression ordinarilyassociated with a single high thermodynamic impedance device. Sucharrangement is shown schematically in FIG. 54. In FIG. 55, line segment705 corresponds to operation of the high impedance compressor and lowimpedance compressor in cascade. Line segment 706 corresponds to a flowso large that the heat transfer within the high thermodynamic impedancegaseous compressor is essentially negligible, and essentially all of thecompression arises from the performance of the low impedancethermodynamic compressor. Region 707 designates, generally, thechangeover between operation of both systems together in cascade anddependence upon the operation of the low thermodynamic impedancecompressor for compression. The system referred to is shownschematically in FIG. 54, where Z_(T) large represents the largethermodynamic impedance gaseous compressor and Z_(T) small representsthe low thermodynamic impedance gaseous compressor. Flow is in thedirection represented by arrows 730.

FLOW VELOCITY AND CONTROL

Thus far, in the discussion of gaseous working fluid rotary inertialthermodynamic devices, it has been assumed that the velocity of flow ofthe working fluid is relatively small compared to the tangentialvelocity of the rotor at the point at which the flow is measured. Whenthe flow velocity for the working fluid becomes an appreciable fraction,or even larger than, the tangential velocity at any point in the rotor,then additional effects appear which are associated with the coriolisforces. These effects can be utilized to concentrate or distribute theregions in which the gas has a range of temperatures or pressures.

FIG. 59 shows a portion of a rotor 1201 which is part of some rotaryinertial thermodynamic device. A conduit 1203-1204 is formed in therotor 1201. Gaseous working fluid is inlet to conduit portion 1203 at1208 and outlet from section 1204 at 1209. The rotor 1201 rotates in thedirection 1206 about the axis 1. Gaseous working fluid progressesradially outward at a low velocity, through conduit means 1203, passesaround a bend 1210 and through a DeLaval nozzle 1202. Upon leavingnozzle 1202 it has a high velocity which is represented by the vector1205. This velocity vector is directed in such a way that its tangentialcomponent 1211 is exactly equal in magnitude and oppositely directed tothe tangential velocity 1207 of the rotor at that point. Thus, seen froma non-rotating frame of reference, the gaseous working fluid has leftonly a radial component 1212. Conduit 1204 is shaped so that as the gasmoves radially inward along the direction of its radial component 1212,the conduit moves exactly the amount necessary to make it lie directlyin the path of the gas, so that the gas experiences essentially notangential momentum interaction with the walls of the conduit. Since itexperiences no appreciable interaction with the walls, and since it doesnot experience any change in velocity (except for some frictionaleffects) in going from the point where it leaves nozzle 1202 to the end1209 of conduit segment 1204, it must have achieved upon exiting nozzle1202 the properties which it has upon reaching point 1209. By utilizingthis contoured conduit, the properties which the working fluid wouldordinarily have only near the center can be extended to a relativelylarge radial region. This is somewhat more difficult to describe withinthe rotating frame of reference, but essentially is equivalent to thebalancing out of centrifugal and coriolus forces with regard to the flowof gas in the contoured conduit.

If the pressure in the gas at the inlet to nozzle 1202 is high enough,flow through the nozzle will be supersonic and there will be a sharpdrop in temperature of the gas at the nozzle exit. Since the shape ofthe duct 1204 prevents expansion of the gas, it will have the same lowtemperature all along duct 1204. This is a highly advantageous featurein many applications.

It is not necessary for nozzle 1202 to produce supersonic flow; for manysituations it is sufficient that conduit 1204 simply be appreciablysmaller in cross-section than conduit 1203, so that the velocity of asubsonic working fluid within it is appreciably higher than it was insection 1203. With such an arrangement, the temperature of the gas insection 1204 also will be relatively low, and will remain substantiallyconstant along the length of section 1204.

That temperature also can be made uniform along the length of a sectionby gradually enlarging its cross section so that the Bernouli effectchanges the pressure in a way that tends to cancel the centrifugallycaused pressure change with radius. In FIG. 63, gas inlet at 4806progresses radially outward in conduit 4801 in direction 4805, inward insection 4802, 4804 and 4803, leaving at 4807. In region 4804, pressureincrease associated with duct cross-section increases balances decreaseof pressure with radius, holding the pressure essentially constant.

It is useful to bear in mind, also, in connection with the control ofvelocity, that the velocity with which a working fluid passes through aconduit affects both the mechanical impedance presented to the workingfluid by that conduit, and also the thermodynamic impedance with respectto the transfer of heat into and out of the working fluid. The use ofthe Bernouli effect, that is, the use of a change in cross-section of aconduit to influence the velocity and pressure of a working fluidflowing therein, is also affected by the location on the rotor. If theeffect is used far out from the axis, the working fluid will typicallybe at a substantially higher pressure.

The use of the coriolis and Bernouli effects allows the distribution ofthe regions within which the heat transfer can be accomplished, and inwhich the working fluid has specific temperatures and pressures orranges of temperatures and pressures. In this way, it can be utilized toaffect the design and construction of impedance control means. It, initself, can be utilized for changing the effectiveness of impedancecontrol means by changing the velocities, pressures, and temperatures ofworking fluids therein. These effects, in turn, are influenced by theangular velocity with which the rotor is rotated. If the rotor isrotated at a very high velocity, then the coupling between thermalchanges in density in the working fluid and mechanical work, in thesense of motion within the rotor, become stronger. If the rotor isrotated at very low angular velocities, this coupling between motion andthermodynamic work becomes smaller.

The use of supersonic nozzles becomes relatively uninteresting when thetangential velocity of the periphery of the rotor is below the sonicvelocity in the working fluid used within its conduits. However, atrelatively high tangential velocities, supersonic nozzles can beutilized in connection with the Coriolis effect, in the manner discussedin connection with FIG. 59. Moreover, the use of a high molecular-weightgas (e.g., one of the "Freons") as the working fluid can significantlyreduce supersonic velocity at which the use of supersonic nozzlesbecomes interesting. Utilization of Coriolis, Bernouli and centrifugaleffects together, is within the scope of the stabilization techniquesbased upon impedance, that is, slowly perturbed states of such systemswill be stable if they satisfy the impedance criteria given previously.

Because the Bernouli effect allows a control of the pressure andtemperature of a working fluid passing through a conduit, in addition toaffecting its velocity, utilization of the Bernouli effect has as one ofits consequences a change in the effective interaction, between heatexchange means of any given temperature and working fluid passingthrough a shaped conduit with a velocity corresponding to a kineticenergy representing a significant portion of its total energy. This, inturn, affects the temperatures at which the thermal energy is acceptedand rejected, which has the effect of varying the thermodynamicimpedance of the gas dynamic process occurring within the rotor.

Consider, for example, the exchange of heat with the gas flowing inconduit 1204, under the conditions described in connection with FIG. 59,in which the component of velocity of the working fluid in the radialdirection is the only non-zero component seen in a non-rotating frame ofreference. In that case, the exchange of heat occurs with a gas havingthe same properties as would be expected relatively near the axis, butover an area ordinarily not available. Or, suppose, at some intermediatepoint designated 1213 in FIG. 59, we were to introduce a somewhatsmaller area ratio in the shape of a convergent and divergent nozzle, soas to convert the flow, once again, to subsonic velocities. Suddenly,the pressure would increase, as would the temperature. By combinationsof these means, intricate rises and falls in temperature and pressurecan be achieved at various points in the rotor.

Similarly to a gas progressing radially inward, a gas moving radiallyoutward with a high velocity can be conducted within a specially shapedconduit such that it does not experience centrifugal and Coriolis forcesuntil it is near the periphery of the rotor. Such a specially shapedconduit 1216-1218 in a rotor 1221 is shown in FIG. 60. Rotor 1221rotates in the direction designated by arrow 1215 about the axis 1. Anozzle 1219 interconnects ducts 1216 and 1218. The tangential velocityof the rotor in the vicinity of nozzle 1219 is designated by vector1220. Gaseous working fluid is inlet from some other part of the system,not shown, at location 1222. It is outlet to some other part of thesystem at location 1223. The velocity of the gas as it enters inlet 1222is entirely radially directed. As the working fluid progresses radiallyoutward, the rotation of rotor 1221 brings each successive portion ofconduit 1216 into line with it, so that it is not deflected by thewalls. In the frame of reference of a stationary observer, the behaviorof the working fluid is as if it were progressing through an essentiallystraight conduit. The working fluid retains essentially the conditionswhich it had at inlet 1217 until it reaches the vicinity of nozzle 1219.Suddenly, its temperature and pressure increase drastically as it isimpacted against the high pressure gases built up in conduit 1218, nearits outer end 1224. This ramming effect does not in any way require thatenergy be delivered from the mechanism providing for the rotation of therotor. The angular momentum transferred to the gas upon its suddenpassage through nozzle 1219 is redelivered by the gas again as itreturns toward axis in the conduit 1218. Effects of this type are mostpronounced when the velocity of the gas and the tangential velocity ofthe rotor are greater than the speed of sound in the gas, because undersuch circumstances, no acoustic wave propagates backwards from thepressure shock at nozzle 1219 to change the properties of gaseous fluidat the entry 1222.

In addition to the extreme cases discussed in connection with FIGS. 59and 60 of minimal interaction between the flowing gas and the walls ofcurved conduits 1204 and 1216, respectively, the principle involved ofcurving the conduit to use the Coriolis effects to influence thebehavior of the gas applies to a much wider range of situations.

In FIG. 61 is illustrated a conduit similar to that shown in FIG. 60.This conduit has a shape which can be of interest in the case of arelatively lower velocity flow of gaseous working fluid. Conduitsegments 1226 and 1227 both are curved to reduce the interaction ofworking fluid with the walls. A bulge 1228 is provided in the conduit.The bulge reduces the flow velocity and converts kinetic energy of thegas into increases in both pressure and temperature. For this reason,heat can be absorbed in region 1228 from a higher temperature heatsource, without irreversible thermodynamic losses, than would be thecase if the conduit were of the same cross-section throughout. The crosssection of the conduit is then again reduced in conduit segment 1227.

It will be seen from the examples given above that for systems with highworking fluid velocities, the various effects associated with theinteraction of pressure, temperature, velocity, and rotation, should betreated in considerable detail. In particular, in cases in whichsupersonic flows are expected to occur, considerable attention should bepaid to the stabilization of the shock waves associated with theconversion between subsonic and supersonic, and supersonic and subsonic,flows. By combining these effects, one could, in principle, constructconduits which have properties not unlike those associated with ramjets, in that a supersonic flow would be converted to a subsonic flow athigh temperature in order to absorb heat from a high temperature heatsource, and then be reconverted to a supersonic flow again at relativelylower temperature. Characterization of the behavior of the heat flowsand mechanical flows associated with such types of operation requires amore detailed timedependent analysis then has been presented so far.However, the gross time independent features of steady state operationshould display the characteristic impedance properties discussedalready, in connection with systems involving lower velocity flows.

THERMODYNAMIC TRANSFORMER

The considerations of thermodynamic impedance and efficiency can beillustrated in a fairly simple example of a thermodynamic transformer.There are many processes in which a mechanism by which useful work isdone has associated with it, intrinsically, a small temperaturedifference. In order to do useful work, a large amount of heat has to betransported thrugh this temperature difference. An excellent example ofthis is the purification of water by evaporative transport. This can beutilized in desalination of sea water, and also in the treatment ofsewage. In both cases the distilled water is a useful product, and theconcentration of the brine remaining, or of the sewage slurry remaining,requires the performance of thermodynamic work. However, for a varietyof practical reasons the maximum input temperature at which such systemsconventionally operate is approximately the boiling point of water,about 100° C. The minimum temperature at which heat is rejected to theenvironment typically is approximately the temperature of the inlet oroutlet fluids, typically in the neighborhood of 20° C. For this reason,the absolute thermodynamic efficiency of the entire process, viewed as aCarnot cycle, is relatively low.

One useful way to raise the efficiency of the process would be to allowthe entire thermodynamic process to accept heat efficiently from ahigher temperature input. To this end, a rotary inertial thermodynamiccompressor can be utilized in a heat transport system acting as athermodynamic "transformer". In such a system, a small amount of heat isutilized in a rotary inertial thermodynamic gaseous compressor toactuate the transport of a large amount of working fluid over arelatively low pressure differential. The working fluid is raised to asufficiently high pressure so that it will condense slightly above thetemperature required for input to the small temperature differencethermodynamic process. The working fluid, after condensation, passesthrough a suitable expansion valve mechanism and is then evaporated at aslightly reduced pressure, so that it evaporates slightly below thetemperature at which the thermodynamic process rejects heat. In thisway, the overall effect is to use a small amount of heat flowing througha large temperature difference, (starting at the input to the gaseouscompressor), to move a large amount of heat associated with thecondensation and evaporation of the working fluid through the smalltemperature difference appropriate to the performance of thethermodynamic work required. This is the "transformer" action referredto above.

FIG. 62 shows schematically a rotary inertial thermodynamic transformer1249 of the type described above. The transformer 1249 includes a rotaryinertial thermodynamic gaseous compressor 1250 actuated by a heat source1256 through a thermodynamic impedance Z1258. Working fluid is outletfrom the compressor 1250, in the direction of arrow 1251, to a condensor1252. From condenser 1252 the heat of condensation is delivered throughtwo impedences, Z1259 which could be a very small load or zero laod,(i.e., high or infinite impedance) which is presumed to be heat rejectedfrom the system entirely; and Z1260, which delivers the heat to a load1261 requiring a small temperature difference. The load 1261 can be, forexample, the evaporator and condenser of a conventional "flash"evaporation desalination plant. Outlet of heat from load 1261 is throughtwo impedances. One of them is an impedence by which heat can berejected from the system Z1263. The other is for the rejection of heatto the evaporator 1254, through an impendence Z1262.

Liquid working fluid flows from condenser 1252 through flow controlmeans 1253 into evaporator 1254. Within the evaporator it evaporates,absorbing heat from the load 1261. Vapor form working fluid proceeds inthe direction shown by arrow 1255 and reenters compressor 1250. For manyapplications, for example, desalination of water or purification ofsewage, it would be desirable to make Z1259 an essentially negligibleloss of thermal energy, and use Z1263 as a heat source for the operationof a cascaded evaporative transport or other thermal purification plant.Alternatively, the process of laod 1261 can represent evaporation acrossa single-stage still, utilizing the impendence conversion in the systemas a whole to allow the process to accept heat efficiently from a hightemperature heat source.

Preferably, the condenser 1252 and evaporator 1254 are stationary. 1265represents some thermodynamic process running on rejected thermalenergy, rejected from the process of laod 1261 through an impedenceZ1263. For example, if load 1261 is the first stage of an evaporativetransport purification plant, subsequent stages might be operated fromthe waste heat therefrom. In that case, 1265 would denote thethermodynamic process of the evaporative purification plant followingthe first stage. Such a plant, by the laws of thermodynamics, mustreject heat to its environment, and the impedace though which it isrejected is desingated Z1264.

Stabilization of the operation of a system of this type depends uponmaking the flow through the total system have a positive impedanceslope. This can be achieved by manipulation of impedance Z1258 and, ingeneral, would occur if high-impedance heat source were used. Most ofthe heat sources of interest for actuating such treatment systems havethe characteristic desired. These include combustion of fuel, nuclearsources,and solar energy sources.

For purposes of comparison, the maximum Carnot cycle efficiency whichcan be obtained, accepting heat at 100° C., are rejecting at a 20° C.,is roughly 22 percent. The maximum Carnot cycle efficiency which can beachieved in a rotary gaseous compressor is appreciably greater thanthat. This allows a substantial increase in overall operatingefficiency. A second characteristic of a transformer system of this typeis that it does not require the utilization of a large number ofcascaded evaporation stages to achieve its high efficiency. Therefore,the way in which efficiency is related to size of plant is not the sameas it is for a conventional cascaded flash evaporation plant. A unit ofthis type can remain efficient even in relatively small sizes, utilizingan impedance matching system of this type for accepting heat from a highimpedance source, efficiently for operating a low impendencethermodynamic load. With the transformer of the present invention, onecan achieve a relatively quite large heat pumping ratio, that is, theamount of heat transported betwen condensor 1252 and evaporator 1254 canbe many times the amount of heat transported from heat source 1256 tothe external heat rejection point through impedances Z1259 and Z1263.

In the case of purification of salt water or sewage, the external heatsink can be the effluent from the plant, be in the purified material orthe rejected concentrated impurities; that is, such materials can havesomewhat higher temperature than those with which they entered theplant, the heat is rejected by this means and no special heat sink isrequired.

There are many low-grade heat processes in which this transformer can beused. For example, the concentration of alcohol, purification of waterby freezing and/or clathrating, and the operation of distillation plantsand related vapor transport purification processes. These processes areamenable to this type of thermodynamic impedance machine, which wouldallow them to be operated with higher efficiency from heat sourceshaving characteristically high temperatures and thermodynamicimpedances.

A thermodynamic transformer of the type shown in FIG. 62 is particularlyattractive in the use of freezing or clathrate formation as apurification technique. It is a technique which requires a relativelysmall temperature difference, but which requires that temperaturedifference in a temperature domain not lending itself to operationdirectly in cascade form from a heat source. For this reason, fairlyintricate systems typically are required to provide efficient operationin an ice type of water purification plant. Also, processes involvingthe utilization of differential solubility of one material in anotherfor purifications typically can benefit from the availability of a largevolume of heat flowing across a small temperature differential.

A transformer system of the type shown in FIG. 62 can also be usedadvantageously for the heating and cooling of large buildings and othertypes of installations utilizing the external environment as a heatsource and/or heat sink. When used for such an application, a system ofthis type offers great flexibility in that the heat pumping ratio,defined as the amount of heat transported divided by the amount of heatdrawn form the heat source, can be varied to take advantage of theoperating conditions so as to always operate with high thermodynamicefficiency. Thus, if there is a small difference between the externalenvironmental temperature and the desired temperature within anenclosure, the heat pumping ratio can be made very large. This allows aconsiderable saving in operating energy. This kind of flexibility isrelatively difficult to obtain using existing absorption cycle systemsor steam ejector type of systems. Very high heat pumping ratios aretheroretically feasible. Moreover, high thermodynamic efficiency couldbe maintained over a relatively wide range of heat pumping ratios.

LOW LOSS REFRIGERATOR

By utilizing a gaseous compressor and a gaseous expansion typerefrigerator, one operating the other and coupled togetherthermodynamically with the other, it is possible to achieve a systemwhich has a relatively low loss, so as to maintain an isolated region atrelatively high pressure while permitting working fluid to flow into itand out from it. FIG. 64 shows such a system. In FIG. 64 the axis ofrotation is 1. Working fluid enters at inlet 1270, passes throughcompressor 1272 into the high-pressure region 1274, thence throughrefrigeration-type heat pump 1273, and out at the outlet 1271. Thetemperature differences for operation of both the compressor 1272 andthe refrigerator 1273 are maintained by the heat flow from heat source1275 through impedance Z1276 into the devices, and out therefrom to aheat sink in the external environment through impedance Z1277. Heat flowbetween devives 1273 and 1272 is indicated by arrows 1278 and 1279.Because of the thermodynamic reversibility of the gaseous compressionand refrigeration processes, device 4810 can equivalently be thought ofas two gaseous compressors back to back, with the high pressure region1274 between them. What is illustrated is the simplest case, a singlestage. By utilizing a large number of stages in cascade, with half thestages operating in the forward direction, followed by a high pressureregion, followed by the other half of the stages operating in thereverse direction, it is possible to achieve in the high-pressure regionextremely high internal pressures and yet have relatively free flow ofworking fluid into and out of that region.

Such a process is interesting for use in chemical reactions, forexample, for the production of ammonia, in which the utilization of ahigh pressure permits the equilibrium point for the chemical reaction tobe appreciably shifted in the direction of the desired product. It isimportant, for an application of this type, that the compression andexpansion portions of the system be in intimate thermal contact witheach other. Thermal losses, in transferring heat from one to the other,give rise to effective pressure losses which must be overcome inmaintaining the pressure. The source of energy for overcoming theselosses is the flow of heat source to some heat sink. It is not necessaryfor the heat sink to be external to the device, provided that there issome way for working fluid to carry off that heat, which, by the laws ofthermodynamics, must be rejected to the environment.

COMPRESSOR STRUCTURES

FIGS. 65 and 66 show a desirable form of construction for rotaryinertial thermodynamic gaseous compressors. FIG. 65 is an exploded viewof the compressor. In FIG. 65, 920 and 922 are impermeable plates made,for instance, of a suitably thermo-conductive material, such as aluminumor some other metal, or beryllium oxide. Core 921 is a circular discmade of a thermally insulating material, for example, a foamed epoxyresin formed as a syntactic foam, a polystyrene foam, or any othersuitable insulating material. Into this material are formed slots, 923,924 (FIG. 66) on opposite faces of the disc. Only a small number ofslots are shown in FIG. 66, for the sake of simplicity. Actually theslots extend completely around the periphery of the disc 921.

Holes 926, 927, 929, etc., are provided in the disc 921 at the ends ofthe slots 923 and 924. This connects one end of a slot 923 with one endof a slot 924 on the opposite side, and the other end of slot 924 withone end of the next upper slot 923, and so forth around the disc 921.Face plates 920 and 922 are bonded to core 921, thereby closing the openfaces of the slots formed therein and forming closed conduits suitablefor carrying working fluid in a spiral path like that illustrated inFIGS. 12 and 13. Selected slots extend radially inward and connect withapertures in face plates 920 and 922 to serve as inlets and outlets. InFIG. 65, the aperture is designated 925 and the radially-extended slotconnecting thereto is designated 930. Construction in this form hasseveral advantages. First, plates 920 and 922 can be formed by simplestamping. Core 921 carries essentially all of the shaped structuredefining the flow conduits. This piece can be formed simply by molding.With this construction technique, the number of parts used to form theassmbled rotary inertial thermodynamic gaseous compressor can beessentially independent of the complexity of the flow paths for theworking fluid within. The device can have many parallel branches, andcan have many stages in each branch. The conduits can be made shallowerand deeper, they can be curved, they can have recesses left within themto accept heat exchange means, magnetic drag means, electromagnetic heatabsorption means, radioisotope heat production means or otherappropriate mechanisms or structures suitable for the stable operationof the rotary inertial thermodynamic gaseous compressor.

In a rotary inertial thermodynamic gaseous compressor formed of threelayers (as shown in FIGS. 65 and 66) the two lids can be utilized asheat exchange surfaces, with one maintained at a relatively hightemperature from which the internal processes absorb heat, and the othermaintained at a relatively low temperature to which the internalprocesses reject heat, in the maner illustrated in FIGS. 12 and 13. Inthis way, thermodynamic connections for heat transfer with the variousimpedance control means within the conduits within such an assemblybecome relatively simple. A particularly desirable form of impendancecontrol means is a set of finely spaced finely spaced fins whichdesirably are formed as part of the lids. For example, fins 1552 on lid920 fit into the ducts when the device is assembled. External fins 1553can be formed in the same way, in a single process if desired. Thesealing properties and most of its structural properties are determinedby the assembly of the three layers 920, 921 and 922. The shaft passesthrough a hole 931 in the assembled device. Alternatively, the devicecan be supported by hubs, or by assembly to some other rotating member.Optionally, the device can be sealed using a conventional type of canseal 1550 near the periphery, formed with extension 1550 of plate 920.

In FIGS. 67 and 68 is shown an alternative form of construction forgaseous compressor utilizing laminations assembled to each other to formducts. In these FIGS. 1001 designates a molded body of insulatingmaterial bearing grooves 1009 which, when covered by a lid 1008, formconduits. In FIG. 67, these conduits, sections of which are 1002 and1003, are seen to contain appropriate impendance control means 1004,1005 and 1007 (e.g. heat exchangers as shown in FIGS. 39 and 40). Acentral hole for a shaft is designated 1006. Selected portions of thelid 1008 or core 1001 can be made thermally conductive to facilitatetransfer of heat into or out of impendence control means, asappropriate.

FIG. 69 shows a preferred gaseous compressor construction utilizinglamination techniques. Laminates in the form of discs 510, 511, 512,513, 514, 517, 518, 519, 520, 521 and 522, together with a core 516,form the conduits for conveying working fluid, and also the impendancecontrol means operative therein. This is illustrated in section 70--70,(FIG. 70) in which can be seen holes 532 and 533 through core 516 forconveying working fluid into and out of impedance control means 520 and531. The impedance control means is constructed by forming elongated,tapered slots in one half of the discs, and forming half-moon-shapedslots in the other half of the discs. Holes 532 and 533 are formed inthe core 516. The discs are assembled with discs having half-moon slotsalternating with those having elongated slots, thus forming thin flowpassageways through which the working fluid can flow.

FIG. 70 shows that the slots are canted at an angle with respect toradii of the disc, so that when two stacks of the discs are formed, onegroup of slots "stage" or move over by one increment, and the facingslots stage over by the remaining portions of the increment necessary tocomplete an entire step, so that the fluid flow first through oneconduit, through core 516, then through the conduit in the oppositestack, through the core again, and then on to the next stage of theconduits in the first stack. In this way, a large number of stages canbe cascaded in a manner analogous to that utilized with a molded coreand discussed in connection with FIGS. 65 and 66.

In a similar manner, laminations 526 can be seen in FIG. 71 to form anexternal set of heat exchange fins. Alternate ones of these fins haveapertures extending out from the center, or extending in from the edge.This leaves a set of blades of the type 540, and a set of apertures ofthe type 539, such that it is possible for air to circulate through thestack. Dotted lines 538 and 537 denote the hidden edges of a set ofapertures hidden behind blade 1300. In this way, stack 536 becomes a setof heat exchange fins for coupling heat to the external environment, inthis case for rejection of waste heat thereto. Apertures 544 are inletswithin intake manifold 508, allowing working fluid to flow into themultiple branches of the parallel-branched gaseous compresseor shown inFIG. 69.

Referring again to FIG. 69, 542 is a shaft. Bearings are at 507 and 524,rotary gas seals are at 501 and 525. Sheaves 503 and 505, belt 504, andmotor 506, serve to rotate the rotary device. Outlet manifold 523 isillustrated diagrammatically in FIG. 72. In FIG. 72, 1301 is the wall ofthe manifold, 1302 denotes generically the outlet ports from the variousbranches of the parallel-branch compressor. 1303 denotes a few of theflap valves utilized to make the operation of this gaseous compressorunconditionally stable.

In FIG. 69, 527 is an anular baffle, utilized in conjunction with burner528 with the inlet 529 to provide heating for the gaseous compressor. Anassembly of this type can be formed from a simple stampings. The variouslaminations can be joined to each other using adhesives or othertechiniques. For example, if the laminations are formed from titanium,or a number of other suitable materials, they can be diffusion bondedinto a hermaticaly sealed stack. In order to avoid the possiblity ofleakage at a large number of external seals, it is possible to use athin outer wall 1304 formed by bringing lamination 510 past thethickness of the compressor to make a single seal, e.g. a conventionaltype of can seal, at location 1305. Although this is shown at just onelocation it is presumed to extend entirely around the periphery of thegaseous compressor device, and form a can having a single seal at theperiphery. In this way, the reliability of the sealing of such a devicecan be greately improved, if desired. Inlet to the entire device is at1306. Outlet from the entire device is at 1307. Flow is in the directiondesignated by arrow 1308. There are many ways in which devices of thistype can be fabricated. For instance, when a lid is formed it can beformed bearing the necessary heat exchange devices upon it, in a singleoperation. Such variations of that type are within the scope of theanalytic technique and principle of impedance control for stabilization.

WORKING FLUIDS

It is to be understood that the working fluid utilized in a rotaryinertial thermodynamic device does not have to be of a single type, suchas a gas or a liquid. It is possible to utilize the thermodynamicproperties of aerosols, so as to delimit in a specified way magnitudeand nature of the temperature dependance upon pressure duringcompression and during expansion.

INTERNAL REACTION FORCES FOR ROTARY DRIVE

In my copending application, I have described various ways in which aclosed loop rotary inertial thermodynamic device can be caused toprovide its own rotation. Quite generally, a rotary inertialthermodynamic compressor can be used to actuate a relative motion withina rotating device, which relative motion can be caused to rotate, orcontribute to rotation of, the rotating device.

One way to do this is to allow a moving working fluid within therotating device to react against a stationary piece, held stationary bysome suitable means, such as a magnet, or gravity. The stationary piecedoes not have to be balanced, and a large amount of wear can betolerated in its support bearing. In FIG. 74 is diagrammed such meansfor rotating a device. 1731 is any suitable rotary inertialthermodynamic compressor, in this case a gaseous device with one stage.1730 denotes generally a rotary drive device, including chamber 1737,inlet tube 1732, jet nozzle 1733, stationary magnetic material bar 1735mounted to rotate on shaft segment 1736 by means of bearing 1738, outlet1739, and magnet 1734. Bar 1735 is kept from rotating by magnet 1734.Compressor 1731 is assumed connected to a larger system, not shown.

High pressure gaseous form working fluid is bled from compressor 1731 atlocation 1741, through conduit 1732, to produce a stream of high speedjet of gas flowing from nozzle 1733 into chanber 1737. Nozzle 1733 isdirected tangentially, backwards from the direction of flow. Thereaction force from the gas drives the nozzle backwards, rotating therotary device. The equal and opposite reaction occurs when the swirlinggas in chamber 1737 strikes stationary bar 1735, which in turn transmitsthis reaction force to magnet 1734, thus removing the opposted reactionforce form the rotary device. Thus, the reaction force against jetnozzle 1733 has no counterbalancing force within the rotary device, andso produces a net torque to rotate it. Note that even relatively severewear of bearing 1738 has little effect on performance of the rotarydrive device. The stationary piece can be extended, with magnets placedsymmetrically about it, so that essentially no component of the magneticforce appears as a load on the bearing. Alternatively, in chamber 1737can be located a balanced magnetic rotor, spun in the reverse sense tothe direction of rotation of the larger rotary device, and serving asthe rotor of an electric generator, whose stator is approximately placedoutside chamber 1737. Electric power production in the generator givesrise to a magnetic drag on the magnetic rotor, consuming the reactionforces from the gas whirling in chamber 1737, and thus serving the samepurpose as bar 1735 with magnet 1734.

From rotary drive 1730 and modification for use as a generator, one canproceed by simple steps to the incorporation of elabrorate mechanicaldevices within the rotary device, operated with working fluid compressedby a rotary inertial thermodynamic compressor. As long as coupling isprovided to allow reaction forces to leave the rotating devices, adriving effect can be achieved. Of course, the use of working fluid forsuch purposes must be included in determining the impedance into whichthe compressor will have to deliver working fluid, and, consequently,the mechanical and thermodynamic impedances throughout the compressor.The ability to use a stationary "rotor" in a turbine or similar deviceoperating within a rotary device can greatly simplify the stationary"rotor". For example, it can be unbalanced. Also, the life of bearingsinside the rotary device, used to support stationary parts within it,can easily be made quite long. Thus, their relative inaccessability,compared to external bearings, is not a severe handicap. The definitionof failure of such bearings is also often much less stringent, becauseof the relative absence of wear-induced wobble.

A secondary pump means can be used to compress a working fluid whichdoes not necessarily condense within the rotary interial device. In FIG.73 is illustrated such a rotary inertial thermodynamic device, 1720. Indevice 1720, 1700 is the inlet, 1714 the outlet, 1704 denotes generallya secondary pump means actuated by rotary inertial compressor 1725, inthis example including nozzle 1702 and diffuser 1703; condensor 1705,evaporator 1708, rotary inertial trap 1707, heat source 1711. Gaseousworking fluid A enters at 1700 in direction of arrow 1701. It iscompressed in secondary pump 1704, in which it mixes with vapor formworking fluid B, which enter condensor 1705 in the direction of arrow1715. In condensor 1705, vapor B condenses, giving up its heat ofcondensation through thermodynamic impedance 1712 to a heat sink notshown, flows radially outward into trap 1707, filling it to some radius1706. Liquid B proceeds in direction of arrow 1719, entering chamber1708 to form annular pool 1709. Liquid B is vaporized by heat from heatsource 1711 through impedance Z1710, returning through conduit 1723 toactuate secondary pump means 1704. Difference in radial location 1722 ofliquid surfaces 1718 and 1706 is associated with operation of device1721 as a compressor, as in FIG. 26. Uncondensedd working fluid A leavesdevice 1720 at 1714 in direction of arrow 1713. Devices of this type canbe combined, with a cooling device with shared condensors, as shown inmy copending application. Used separately, a device 1720, with suitablydesigned secondary pump means, can be used as a vacuum pump, compressor,etc. Inlet 1700 and outlet 1714, of course, do not have to be on axis 1.Stable operation of a device of this type depends on stable operationsof its rotary inertial thermodynamic portion, and thus on the mechanicaland thermodynamic impedances of the device and the total system of whichit is a part.

As can be seen from FIG. 26, it is important in the design of heatexchange chambers to consider the tendency of liquid to move radiallyoutward. For this reason, it is highly desirable that ports for gasinlet and outlet be located radially inward from those through whichliquid passes. This same design consideration applies to the details ofheat exchange means and, more generally, impedance control means.Following this design practice avoids unwanted back-pressures andthermodynamic inversibilities associated with forcing a gas to bubbleradially inward through a liquid.

GENERAL ANALYTICAL MODEL OF SYSTEM

FIG. 75 shows schematically the analytic strucure of a rotary inertialthermodynamic system, identified by its acronym "RITS" in FIG. 75. Thesystem is depicted as including a rotary inertial thermodynamic device1350, (designated RITD) having within it internal mechanical impedancesdesignated generally by [Z_(M) INT] to denote that there can be aplurality of such impedances and internal thermodynamic and impedancesdesignated [Z_(T) INT] a geometric configuration represented by G. Inputto this system is an angular velodity designated W, and operating inconjunction therewith are mechanical impedances external to the deviceand thermodynamic impedances external to the device, designatedgenerically Z_(M) EXT. and Z_(T) EXT., respectively. The performances ofthe rotary inertial thermodynamic device is affected by all of theseimpedances. The conditions set forth in this patent application areappropriate for the analysis of all rotary inertial thermodynamicsystems of this general form. A number of selected examples have beengiven in the disclosure in order to show the generality of the method ofanalysis, and illustrate ways in which they can be applied in specificcases. The applications in these cases serve also to illustrate thegreat advantages which rotary inertial thermodynamic systems possess fora wide variety of applications of practical importance.

It is to be understood that although specific details have beendescribed in the context of examples, the various features disclosedherein can be used in combination with each other and can be extended inways which will be apparent to workers in the field, without departingfrom the technique of stabilization of flow of working fluid within arotary inertial thermodynamic device by controlling its internal andexternal mechanical and thermodynamic impedances.

I claim:
 1. A rotary thermodynamic system including a rotatable fluidflow conduit having radially outwardly-directed and inwardly-directedsections in which conduit the thermodynamic pressure drop decreases withan increase in the rate of flow of working fluid through said system,and impedance control means for providing an increase of pressure dropfor an increase in the rate of flow of working fluid through saidconduit, the amount of said increase in pressure drop being effective tocause the overall pressure drop for said system to increase with anincrease in said rate of flow, and thereby stabilizing the flow ofworking fluid through said conduit.
 2. A system as in claim 1, saidimpedance control means including means for controlling the heatexchange between said rotary thermodynamic device and the environment.3. A system as in claim 1 including heat exchanger means providingmultiple heat conducting surfaces in said conduit.
 4. A system as inclaim 1 in which said rotary thermodynamic device has a plurality ofsaid conduits connected in parallel, and a flow-restricting heatexchanger in each of said conduits.
 5. A system as in claim 3 in whichsaid impedance control means includes means for controlling themechanical impedance to fluid flow in said system.
 6. A system as inclaim 5 in which said system includes a positive-displacement pump forpumping working fluid through said conduit.
 7. A system as in claim 6 inwhich said pump is a reciprocating piston pump.
 8. A system as in claim6 in which said pump is a sliding vane pump.
 9. A system as in claim 1in which said impedance control means includes means for controlling thethermodynamic impedance of said system.
 10. A rotary thermodynamicsystem including a rotatable fluid flow conduit having radiallyoutwardly-directed and inwardly-directed sections, impedance controlmeans for providing an increase of pressure drop for an increase in therate of flow of working fluid through said conduit and therebystabilizing the flow of working fluid through said conduit, heatexchanger means in said conduit, said heat exchanger means comprising atleast one group of parallel contiguous tubes forming in said conduitplural flow passageways each of a cross-sectional area smaller than thatof said conduit.
 11. A system as in claim 10 in which said tubes aresubstantially polygonal in cross-sectional shape.
 12. A system as inclaim 10 in which said tubes have a wall thickness which is smaller nearthe center of said conduit than it is adjacent the walls of saidconduit.
 13. A method of stabilizing the operation of a rotarythermodynamic system including a rotatable fluid flow conduit withradially outwardly-directed and inwardly-directed sections, there beinga decrease in the pressure drop in said conduit with an increase in therate of flow of working fluid through said conduit, said methodcomprising controlling the flow impedance in said system so that thereis an increase in pressure drop for an increase of the flow rate ofworking fluid through said system, said increase being greater than saiddecrease so as to give said system an overall pressure drop whichincreases with increases in said flow rate.
 14. A method as in claim 13in which said controlling step comprises controlling the thermodynamicimpedance of said system.
 15. A method as in claim 13 in which saidcontrolling step comprises controlling the mechanical impedance to fluidflow in said system.
 16. In a rotary thermodynamic device having aplurality of parallel-connected conduits, each having a first sectionextending outwardly from a common rotational axis, and a second sectionextending inwardly towards said axis, rotary drive means for rotatingsaid conduits about said axis, means for extracting heat from a workingfluid flowing outwardly through each of said outgoing sections, meansfor pumping said working fluid outwardly from said axis through each ofsaid outgoing sections and inwardly towards said axis, the back-pressureof said working fluid in said inwardly-extending section due to theaction of centrifugal force being greater than the forward pressure ofsaid fluid in said outgoing section due to centrifugal force, thedifference between said forward and back pressures being called thethermodynamic pressure drop, said thermodynamic pressure drop decreasingwith increasing flow rate through said conduits, and means forrestricting the cross-sectional areas of said conduits in an amounteffective to give an overall increase in the total pressure drop in thefluid with increasing rates of flow.
 17. In a rotary thermodynamicdevice having at least one fluid flow conduit having a first sectionextending outwardly from a common rotational axis, and a second sectionextending inwardly towards said axis, rotary drive means for rotatingsaid conduits about said axis, means for pumping said working fluidoutwardly from said axis through said outgoing section and inwardlytowards said axis, the back-pressure of said working fluid in saidinwardly-extending section due to the action of centrifugal force beinggreater than the forward pressure of said fluid in said outgoing sectiondue to centrifugal force, the difference between said forward and backpressures being called the thermodynamic pressure drop, saidthermodynamic pressure drop decreasing with increasing flow rate throughsaid conduits, and impedance means for partially blocking the flow offluid through said conduit and thereby increasing the mechanicalimpedance to flow through said conduit in an amount effective to give anoverall increase in the total pressure drop in the fluid with increasingrates of flow.
 18. A device as in claim 17, in which said impedancemeans comprises a heat-exchanger with at least one passageway ofcross-sectional area substantially smaller than that of said conduit.19. A device as in claim 18 in which said heat-exchanger has a pluralityof said passageways.